
Elves are one of the less-impacted factions by Warriors of the North/Ice and Fire, but that doesn't mean there's no impact. It's just less in-your-face than some.
Morale-wise...
-2 Morale for Demonic presence in allies.
-3 Morale for Undead presence in allies.
-1 Morale for Dwarven presence in allies.
-1 Morale for Orc presence in allies.
-1 Morale for Lizardmen presence in allies.
-1 Morale for Viking presence in allies.
-3 Morale for Undead Lizardmen presence in allies.
+1 Morale if the army is made solely of Elves and Snow Elves.
... they hate Demons and Undead more than in Armored Princess, and remain pretty hostile to outsiders in general, but that commented-out mechanic of Humans and Elves getting along extra well has finally been implemented in the form of Elves and Snow Elves getting along extra well! (Said commented-out bit of code has been removed entirely for the Elf/Human end of things, though)
Elves themselves have finally picked up a factional Ability:
Elemental Power
At the beginning of the battle, all Elves are randomly assigned Fire, Water, Earth, or Wind as a 'type'. Each of these provides a fixed bonus. Specifically...
Earth provides +20% to Health and Defense
Wind provides +1 Speed and +15% crit chance
Fire provides +20% to base Attack and +15% resistance to Fire
damage.
Water provides +1 Initiative and +15% resistance to Poison
damage
Elemental Power is, unfortunately, notably bugged. First of all, Water is supposed to provide 15% Magic
resistance in addition to Poison, but is bugged so it doesn't work. Second, Fire is supposed to provide 15% Ice
resistance, but is also bugged so it doesn't work. The other bugs require getting into how Elemental Power actually works, as under the hood it's a bit more complicated than just '25% chance to roll any given element' and the bugginess is tied to this.
The thing is, the game divides Elves into 6 sub-groups. Each sub-group has its own weightings for elemental outcome, and the game actually rolls the element for the sub-group as a whole; for example, if your Forest Fairies got the Earth bonuses, so too did your Ancient Ents.
As for those sub-groups and their odds...
Team Water: Unicorn, Black Unicorn, Lake Fairy.
35% chance for Water, 25% chance for Earth, 25% chance for Wind, 15% chance for Fire
Team Tree: Forest Fairy, Ent, Ancient Ent.
35% chance for Earth, 30% chance for Water, 25% chance for Wind, 10% chance for Fire
Team Archer: Elf-the-unit, Ranger, Avenger.
35% chance for Wind, 25% chance for Earth, 20% chance for Water, 20% chance for Fire
Team Heavenly Bodies: Werewolf Elf in either form, Sun Fairy.
40% chance for Fire, 25% chance for Wind, 20% chance for Earth, 15% chance for Water
Team Treehugger: Druid, Dryad.
Even split for all elements... except it's mis-coded so Water's entry is another Earth entry, so actually it's a 50% chance for Earth and a 0% for Water.
Team Alone: Faun.
Also mis-coded, with no entry for Earth and duplicate entries for Water. Works out to a 65% chance for Water, 25% chance for Wind, 10% chance for Fire. (The duplicate entries are a 35% and 30% chance, for reference)
Note that I've completely made up these 'team names', though aside the Faun the names are pretty direct reflections of what seems to have been the thought process behind the groupings.
One takeaway of all this is that Fire is rare; only Werewolf Elves and Sun Fairies place it higher than 'worst odds' or 'tied for worst odds'. It's also a little awkward that the team that most favors Wind is a bunch of unlimited-range archers... the thematics are cute, but also hidden from the player, and mechanically not ideal. On the plus side, Ents and Ancient Ents do want Earth more than any other and get it more than any other. Team Water is awkward, but primarily because Water is bugged to not give Magic resistance; all three of its units have 25% Magic resistance, and so could put to use another 15% Magic resistance a lot more than some of the Elves out there. But whoops, bugged.
Elemental Power is more content lifted from Red Sands, though the Red Sands version was more consistently influential, having more pronounced boosts and also throwing in each element causing the unit to start with a specific buff active for three turns. (eg Earth gave Stone Skin) I'm not sure why they scaled it back, honestly. Wind and Water can be gamechangers, but Earth and Fire are so ignorable I sometimes forget to pay attention to Elemental Power, and on ranged units only Water is all that significant... and only if it bumps them up over some enemy unit or another, which isn't guaranteed.
Still, it's nice that Elves have something to them, even if I'd have preferred something a bit more interesting.
And less bugged.

Lake Fairy
Level: 1
Hiring Cost: 16
Leadership: 7
Attack/Defense: 3 / 3
Initiative/Speed: 7 / 5
Health: 8
Damage: 1-2 Magic
Resistances: 25% Magic
Talents: Hunter's Mark (Charge: 1. Applies Hunter's Mark to every enemy. Archers that fire on such marked units will automatically get a critical hit)
Abilities: Soars, No retaliation, Magic Resistance (25% Magic resistance), Fairy Dust (Melee attacks have a 30% chance of inflicting Weakness for one turn), Elemental Power
They picked up Elemental Power. That's it.
It's worth noting however that Warriors of the North is the only game in the series to have four archers that can collectively benefit from a Morale bonus alongside Lake Fairies. Team up Lake Fairies with Elves-the-unit, Rangers, Avengers, and Snow Elf Scouts, and Hunter's Mark can be used to just absolutely murder Marked units, particularly if you're a Viking with ranks in Absolute Rage.

Forest Fairy
Level: 1
Hiring Cost: 20
Leadership: 9
Attack/Defense: 4 / 2
Initiative/Speed: 5 / 4
Health: 9
Damage: 1-3 Magical
Resistances: 25% Magic
, -50% Fire
Talents: Dispel (Charge: 1. Dispels all effects on a single arbitrary unit)
Abilities: Soars, No retaliation, Magic Resistance (25% Magic resistance), Susceptible to fire (-50% Fire resistance), Oblivion (Melee attacks have a 50% chance of temporarily disabling all the target's Talents), Elemental Power
Only change is gaining Elemental Power.
Unlike Lake Fairies, context hasn't really offered any interesting changes.

Werewolf Elf (Elf form)
Level: 3
Hiring Cost: 160
Leadership: 60
Attack/Defense: 16 / 16
Initiative/Speed: 5 / 2
Health: 55
Damage: 7-9 Physical
Resistances: Generic.
Talents: Transformation (Reload 2: Switch forms)
Abilities: Blades (Inflicts Bleeding on melee hits), Night Sight (+50% Attack at night and/or underground), Regeneration ('Top' member of the stack fully heals at the start of their turn), Tolerance (No Morale penalty from Undead allies), Vampire Despiser (+30% damage to Vampires and Ancient Vampires in either of their forms), Elemental Power
Picked up Vampire Despiser and Elemental Power. No other (Direct) changes to this end.
Vampire Despiser will actually be relevant fairly regularly, as Vampires and Ancient Vampires are quite common in Undead battlegroups and Undead battlegroups are dense in many parts of Warriors of the North. It's only a modest increase in damage output, but it's there.
More important and interesting, as noted before, is that Bleeding now inflicts percentile Physical damage! Furthermore, it lowers enemy maximum Health instead of lowering Attack and Defense, making it a multiplier to Rage and Spells and just generally making the target die faster if you follow up.
This is kind of annoying on AI Werewolf Elves since it means they're quite prone to eg causing a casualty through Bleeding even though the initial hit was insufficient, but honestly I appreciate it regardless. For one thing, it makes it easier to keep track of what units are suffering from Bleeding, making it easier to remember who you should be targeting first for maximum casualty infliction. For another, Bleeding doing damage over time actually shifts how you prefer to use Werewolf Elves: you should be trying to spread around the hits to maximize Bleeding-derived damage, even if you aren't going to follow up with unit attacks.
Plus, it's just natural and intuitive that someone bleeding heavily is actively suffering directly from the bleeding itself. Bleeding only lowering Attack and Defense has always felt weird in the prior games, even before I got to Warriors of the North and got used to it being a damaging effect.
A more subtle difference is that Blades triggers on counterattacks now; it didn't in previous games. (Though with how mild Bleeding was in them, I imagine most players didn't notice)

Werewolf Elf (Wolf form)
Level: 3
Leadership: 60
Attack/Defense: 16 / 10
Initiative/Speed: 5 / 4
Health: 55
Damage: 5-8 Physical
Resistances: -10% Fire
, 10% Ice
Talents: Howl (Charge: 1. All enemy Humans, Elves, and Dwarves of Level 1-2 are hit with Fear, and additionally have a 50% chance of skipping their turn entirely), Transformation (Reload: 2. Switch forms)
Abilities: Beast (-10% Fire, 10% Ice) Night Sight (+50% Attack at night and/or underground), Frenzy (20% chance to inflict Frenzy for 1 turn on melee attacks. Frenzied units are hostile to all units, but the effect ends after the first time they attack something), Regeneration ('Top' member of the stack fully heals at the start of their turn), Tolerance (No Morale penalty from Undead allies), Vampire Despiser (+30% damage to Vampires and Ancient Vampires in either of their forms), Lycanthrope (When melee attacking humanoid units, there is a 30% chance that 25% of the units killed in the attack will join the Werewolf's stack. At night or underground 50% of the units killed will join instead. Spellcaster units such as Druids and Priests can't be converted), Elemental Power
They've picked up the Beast Ability, giving them a minor Fire weakness and a minor Ice resistance, and of course have picked up Elemental Power and Vampire Despiser. Their Abilities are also more specific about eg what Lycanthrope can effect, but outside of affecting new units I'm not aware of them having a change.
Notably, Warriors of the North is really the first game where Werewolf Elves are generally better off in Elf form than Wolf form as much as possible. It can be a good idea to open a battle by transforming, closing in, and Howling if that's an option (It's not an option very often in Warriors of the North), then transforming back once you're close enough for Elf form to mix it up with enemies, but where in prior games wolf form's mobility and potential to inflict Frenzy tended to make it the more appealing choice outside of like fighting Orc Hunters or the like, in Warriors of the North Bleeding is such a big edge to be spreading around that it's just plain biased toward Elf form. This notably has the effect of making regular Wolves a bit less unappealing: if you want to use Werewolf Elves but you also want Howl, it might be better to bring Wolves to handle Howl and Teleport the Werewolf Elves into melee or the like. This was never really much of a plausible scenario in prior games, but now it is!
Lycanthropy has also had its range of possible targets expanded. It's now...
Peasants, Robbers, Marauders, Bowmen, Swordsmen, Guardsmen, Horsemen, Knights, Lake Fairies, Forest Fairies, Dryads, Elves-the-unit, Hunters, Pirates, Sea Dogs, Assassins, Slingers, Skalds, Vikings, Berserkers, Axe Throwers, Jarls, Sun Fairies and Avengers
So basically most Vikings are included, as are the new humanoid Elves. Too bad you don't fight Vikings very often. Nor Humans. Really, even though the list is expanded, I think you may get fewer battles to try it in, in real terms... one of many examples of Warriors of the North's focus on Undead as enemies having unfortunate effects.
Interestingly, Frenzy/Rabid no longer has a Level limit. Now you can feel free to get excited about turning enemy dragons upon your foes! You know, 20% of the time. More importantly, don't think having your Level 4 or 5 units provoking retaliations from enemy Werewolves is relatively safe the way it was in previous games.
Also note that Vikings are in fact considered humanoids for Howl's purposes... and Snow Elves aren't! This latter point is almost certainly an oversight or product of rushing or some such.

Unicorn
Level: 4
Hiring Cost: 550
Leadership: 130
Attack/Defense: 23 / 20
Initiative/Speed: 7 / 5
Health: 120
Damage (Default): 9-15 Physical
Damage (Horn of Light bonus): 3-6 Magic
Resistances: 25% Magic
Talents: None
Abilities: Magic Resistance (+25% Magic resistance), Horn of Light, (Adds Horn of Light bonus damage when attacking Undead, Demons, or Undead Lizardmen) Defender of Beauty (+2 Morale to Dryads, Lake Fairies, and Forest Fairies), Elemental Power
They've lost some minimum and maximum damage in exchange for Elemental Power. Er. Good trade?
Yes, Defender of Beauty still only affects those three units. It does not affect Sun Fairies, Snowflake Fairies, or Ice Nymphs. I don't really get it either, and it's a bit disappointing since one of the problems with Defender of Beauty has always been that maximizing it involves having something like 75% of your unit-derived damage output be Magical. Snowflake Fairies breaking that up a bit would be nice and make Unicorns a bit more appealing. (As would Sun Fairies if they did the Fire damage you'd expect them to do...)
To be fair, Horn of Light is way more reliably useful than in prior games, as Undead are all over the place, but Warriors of the North is probably the most egregious in the series about Black Unicorns tending to shunt aside Unicorns.

Black Unicorn
Level: 4
Hiring Cost: 750
Leadership: 150
Attack/Defense: 27 / 24
Initiative/Speed: 5 / 4
Health: 140
Damage (Default): 11-20 Physical
Damage (Horn of Light bonus): 4-7 Magic
Resistances: 25% Magic
Talents: None
Abilities: Magic Resistance (25% Magic resistance), Horn of Light (Adds Horn of Light bonus damage when attacking Undead, Demons, or Undead Lizardmen), Tolerance (No Morale penalty from allied Undead), Blood for Blood (Retaliatory strikes always crit against units that aren't Elves-the-species), Elemental Power
Their damage has dropped slightly. Other than that and Elemental Power being added, they're actually the same. Blood for Blood actually gives the correct description in-game, but mechanically it hasn't changed.
As with other auto-crit effects, Black Unicorns perform particularly well in the hands of a Viking via Absolute Rage raising crit damage, and since Undead are all over the place, susceptible to Horn of Light, and of course are not Elves... Black Unicorns can be impressively deadly in a melee with Undead. This does carry the caveat that Vampires and Ancient Vampires have No Retaliation and Necro Energy Blast is found on a bunch of Undead and is an attack that doesn't provoke a retaliation, so Black Unicorns aren't quite as ridiculous against Undead as you might hope (Especially since Zombies and Decaying Zombies are prone to Passing to a ranged attacker and Bone Dragons have a no-retaliation Talent...) but they're potentially really solid in general and especially for the Viking if you don't mind having to do something to cope with the casualties they'll be taking.
This is probably the high point for Black Unicorns, in fact.

Dryad
Level: 2
Hiring Cost: 50
Leadership: 20
Attack/Defense: 4 / 12
Initiative/Speed: 4 / 3
Health: 25
Damage: 1-3 Magical
Resistances: Generic.
Talents: Summon Thorns (Reload: 2. Generates a Thorn Hunter or Thorn Warrior stack in a chosen adjacent tile with a total Leadership of 8-10 per Dryad in the summoning stack), Elven Song (Charge: 1. All Elven allies have +3 Initiative for 5 turns), Lullaby (Reload: 3. All enemies below Level 4 that are not immune to Mind effects and are below 30 Leadership per Dryad fall asleep for 1 turn)
Abilities: Soaring, No retaliation, Beauty (30% chance for enemy humanoid males to Miss when attacking the Dryad), Charm (Melee attacks have a 20% chance to temporarily convert male humanoids below Level 4 into allies), Wood Fairy (+1 Morale for allied Plants and Fauns), Oblivion (Melee attacks have a 50% chance of temporarily disabling all the target's Talents), Elemental Power
They've switched back to their The Legend graphic, Lullaby finally has a Leadership cap so that those last 30 Dryads don't put your 500 Imps to Sleep anymore, Wood Fairy boosts Fauns now, and... that's it. (Aside Elemental Power, of course) I'm fine with that, and even the graphical end is understandable, as Snow Elves have a Dryad of their own to steal the Armored Princess graphic. An extremely minor change is that Charm has been tweaked to be able to trigger against targets whose Leadership is exactly equal to the Dryad stack's, not just stacks with less Leadership; this will basically never matter, but hey.
Seriously, I'm really glad Lullaby has a Leadership cap. Dryads have long been crazy-making as one of those rare unit types that can seriously screw up your battle plans even though you wiped out 80% of the stack, between Lullaby and Elven Song, and while Elven Song is still around to be incredibly aggravating, Lullaby was always the primary offender.
Aside from that relief of a change, the only other particularly notable point is that Dryads perform especially well against Drunken forces. They will dodge more often than not, and actually have a respectable chance of Charming an enemy. So basically Dryads are a little more tempting when you're running around areas heavy on Dwarves, and when you're in one of the (relatively few) parts of the game where Dryads are running about you might want to switch away from an all-Dwarves army so the RNG stops murdering you. It's a fairly situational thing, but I kind of like it anyway. It's one of the few cases where I'm genuinely a bit irked by how common Undead are as enemies -if there was more space devoted to Dwarves and Elves as enemies you fight, this would be a fairly cool mechanic. As-is, it's entirely possible you'll never see the interaction in action even if you're fond of Dwarves and/or Elves.
A minor note: Ice Thorns are a new Plant in Ice And Fire, and they don't get a Morale boost from Dryad presence. This is a bug. Ice Thorns are difficult enough to justify using directly this isn't particularly impactful, but still...

Ent
Level: 4
Hiring Cost: 800
Leadership: 260
Attack/Defense: 30 / 36
Initiative/Speed: 2 / 2
Health: 260
Damage: 25-30 Physical
Resistances: 10% Physical
, 50% Poison
, -100% Fire
Talents: Running (Charge: 1. +1 Action Points), Swarm (Reload: 1. Ranged attack with an effective range of 4 which does 12-15 Physical
damage and 12-15 Poison
damage to a single target)
Abilities: Plant (+100% vulnerability to Fire, +50% resistance to Poison, immunity to mental effects, assorted secondary implications), Entangle (50% chance to Entangle enemies with melee attack, reducing AP to 1 for 2 turns), Wooden (+10% Physical resistance), Elemental Power
The only changes are picking up Elemental Power and the non-change of Wooden, which is just the game explicitly mentioning via Abilities a thing Armored Princess already made true.
Something that's not a change but that's more important in Warriors of the North is that Plants are all immune to Bleeding. Bleeding can still only be inflicted by a handful of units, but since Bleeding now inflicts percentile damage when it does crop up its impact is a lot larger: in prior games, if a Bleeding unit didn't attack and wasn't attacked while Bleeding, the Bleeding didn't do anything. Not so in Warriors of the North. This makes Plants more appealing when you are fighting Werewolf Elves or their Snow Elf equivalent... and those aren't actually the only sources of Bleeding infliction, though they're by far the most notable.
Overall though they play more or less as they did in Armored Princess, outside that rolling Wind can dramatically enhance their effectiveness as a melee unit. Though not nearly so much as...

Ancient Ent
Level: 5
Hiring Cost: 3600
Leadership: 1200
Attack/Defense: 50 / 60
Initiative/Speed: 1 / 1
Health: 1400
Damage: 100-140 Physical
Resistances: 10% Physical
, 50% Poison
, -100% Fire
, 20% Ice
Talents: Swarm (Charge: 1. Does 50-90 Physical
and 50-90 Poison
damage to a single target with an effective range of 4. Cannot be used if an enemy is adjacent), Summon Swarm (Reload: 1. Recharges Swarm), Running (Charge: 1. +2 Action Points)
Abilities: Plant (+100% vulnerability to Fire, +50% resistance to Poison, immunity to mental effects, assorted secondary implications), Wooden (+10% Physical resistance), Cold Protection (+20% Ice resistance), Entangle (50% chance to Entangle enemies with melee attack, reducing AP to 1 for 2 turns), Elemental Power
Ancient Ents have gained Ice resistance now that Ice is properly a thing, had their Physical resistance officially acknowledged in Ability form, and of course picked up Elemental Power.
Ancient Ents are one of the more notable beneficiaries from Elemental Power, not to mention the level mechanics. As a Level 5 unit, they can get Speed from leveling, finally allowing them to consistently advance even while launching and summoning Swarms (Though the AI won't take advantage of this...), while Elemental Power they're actually happy with basically every possibility. Earth giving them more monstrous of Health? Sure, they love to tank! Wind giving them additional Speed? Time for even an un-leveled Ancient Ent to march every turn! Fire making them more lethal and making them less egregiously vulnerable to Fire? Awesome. (It would be more awesome if the Ice resistance actually worked...) Water bumping them out of the completely awful Initiative tier of 1, not to mention extending their durability vs Poison by more than 20%? Okay, a bit situational on both ends, but certainly not bad, and among other points since Undead are routine foes jumping out of 1 Initiative is plenty relevant given Zombies and Decaying Zombies.
As such, Warriors of the North is actually probably the high point of the series for Ancient Ents. If ever you wanted to use them in these games, Warriors of the North is the favored possibility to give it a go.

Elf
Level: 3
Hiring Cost: 270
Leadership: 80
Attack/Defense: 21 / 15
Initiative/Speed: 5 / 2
Health: 60
Damage: 4-5 Physical
Resistances: Generic
Talents: Double Shot (Reload: 2. Ranged attack that does 8-10 Physical
damage to a single target)
Abilities: Archer, Sniper (Unlimited range), No Melee Penalty, Light Steps (Traps do half damage to this unit), Elemental Power
They've picked up Light Steps and Elemental Power.
Light Steps is even more eeeeeh on them than it was on Robbers and Marauders, as Elves rarely have cause to walk into Traps in the first place. I like it on a lore level, but it doesn't really add anything to the gameplay.
Elves are one of the units that finds Elemental Power most disappointing. Fire is good for damage, Wind can potentially be good if enemies try to pin your Elf stack, Water might have Initiative tiers line up, and Earth is only good if they're getting beat up which they really shouldn't be. This largely boils down to them being built as chiefly a ranged unit -I could say the same about all the other Elven ranged units like Rangers and Avengers and Druids. I just find it particularly weird or ironic that Elves-the-unit get so little benefit from the racial unique of Elves-the-species.

Ranger
Level: 4
Hiring Cost: 700
Leadership: 150
Attack/Defense: 27 / 18
Initiative/Speed: 6 / 2
Health: 110
Damage (Default): 8-12 Physical
Damage (Hunter): 12-16 Physical
Resistances: Generic
Talents: Poisoned Arrows (Charge: 1. Standard ranged attack that does 8-12 Poison
damage and automatically Poisons the target. Against 'beasts' does 12-16 Poison
damage instead, and still Poisons the target)
Abilities: Archer, Sniper (Unlimited range), No Melee Penalty, Hunter (Calls the Hunter attack when attacking 'beasts' at range), Light Steps (Traps do half damage to this unit), Elemental Power
Hunter Ranger damage range has been widened a point in each direction, making them less stable, but their peak performance is higher -and since there's multiple ways to force crits, even within the Elven forces (ie discounting Doom and ignoring non-Elf units they probably don't get along with because Elves), that's overall an improvement. Plus they have a Talent now!
A bizarre point is that a Ranger firing Dragon Arrows doesn't get the Hunter damage bonus, but a Ranger firing Poisoned Arrows is just fine on that count. (Because the devs didn't code up a seventh attack to cover 'Dragon Arrows against beasts' -yes, under the hood the Ranger has six attacks) As such, the Ranger really shouldn't be firing Dragon Arrows on animals; 99% of the time their base attack will do noticeably more damage.
A similar oddity is that Poisoned Arrows is special-cased to ignore the damage reduction from Bone! (Amusingly, this includes its invisible anti-beast form, even though no unit is a beast with Bone) As Bone's 70% damage reduction is greater than the default Undead 50% Poison resistance, this means Poisoned Arrows actually hits harder against Skeletons, Skeleton Archers, and Bone Dragons than the Ranger's normal attack. So don't just ignore Poisoned Arrows when fighting Undead.
Overall though the big change is that Poisoned Arrows lets Rangers contribute more effectively against a number of Physically resistant units. This... is less dramatic of a point than one might hope, as Warriors of the North is heavy on Undead (All Poison resistant) and light on Humans. (One of the main clusters of good-to-solid Physical resistance) Lizardmen have picked up Physical resistance, but they still commonly take halved damage from ranged attacks so that's not much help. It's not until you're fighting Dwarves and Vikings in the late game it tends to stand out as an advantage in that regard. Mostly you'll use Poisoned Arrows for the part where they inflict Poisoning, prior to that point. It's a little frustrating, and one example of how I'd really like Warriors of the North's general design used as the basis of a new story. One that's not so heavy on Undead.

Druid
Level: 3
Hiring Cost: 240
Leadership: 100
Attack/Defense: 16 / 22
Initiative/Speed: 2 / 2
Health: 100
Damage (Ranged): 4-8 Magic
Damage (Melee): 2-4 Physical
Resistances: 25% Magic
Talents: Summon Bear (Reload: 2. Summons a stack of Bears or Ancient Bears, whose stack size is determined by having their Health be 25-35 per Druid in the casting stack), Training (Charge: 1. Take control of an enemy animal stack whose Level is 1-3, whose Leadership total is 80 or less per Druid in the casting stack. The control lasts for 2 turns), Natural Healing (Charges: 2. For three turns, a single target ally is healed at the beginning of its turn for 10% of its maximum health. The healing is also increased by 1% for every 10 Druids in the casting stack, up to a maximum of 20%. Cannot be cast on Undead, Undead Lizardmen, Plants, or units immune to magic)
Abilities: Sting of the Forest (Range: 6. Ranged attack splashes to adjacent enemies with no friendly fire. The splash damage is only 50% of base), Magic Resistance (25% Magic resistance), Aura of Harmony (+1 to Morale for allied Elves), Light Steps (Traps do half damage to this unit), Elemental Power
So apparently Druids were still not good enough for the developers, as they now summon even more bears at a time, picked up Natural Healing and Light Steps, and of course have gotten the universal Elemental Power.
Light Steps is of course still largely-irrelevant, and Natural Healing is, uh... existent? Like okay yes you fight Necromancers a lot and so get Plagued a lot in Warriors of the North, but purging Plague on a single unit is only mildly nice when Necromancers are hitting your entire army. Sure if you're a mono-Elf army this might include two trees immune to Plague, but that's still three units you'd like purged. And Plague only lasts two turns normally anyway, so even though Natural Healing has two charges it's not really worth using the second one... and Natural Healing is bugged to not actually remove Plague anyway! While the healing part is... pretty minor. This is healing the top stack member, no resurrections or anything. It can be okay on an Ancient Treant because they're ridiculously durable (Oh, wait, they're invalid targets! arrrgh), but on most units you'd probably extend their durability further by having the Druids lob their weak attack at whatever is capable of threatening the unit you're considering healing. I like the idea behind Natural Healing, but I really think it should've had different mechanics. Preferably something incorporating resurrection.
The net result is that the primary change of importance is that they summon more bears when summoning bears.

Faun
Level: 2
Hiring Cost: 80
Leadership: 60
Attack/Defense: 16 / 15
Initiative/Speed: 3 / 4
Health: 23
Damage (Ranged): 3-5 Magical
Damage (Melee): 3-5 Physical
Resistances: 10% Magic
, -10% Fire
Talents: Faun Magic (Charges: 2. Can heal an adjacent Plant for 12 Health per Faun in the healing stack, potentially reviving the dead), Fatigue (Reload: 3. An enemy stack below Level 5 whose Leadership is less than 90 per Faun in the casting stack is put to Sleep for 2 turns), Nightmare (Reload: 1. An arbitrary sleeping foe takes 7-12 Magic
damage, and immediately awakens)
Abilities: Enchanted Projectile (Range: 4. The Faun's ranged attack lowers the target's Attack and Defense by 1 for the rest of the battle. This effect stacks to a maximum of -10), No Melee Penalty, Fears Darkness (-2 Initiative at night and underground), Spirit of the Wood (Doubled damage against enemy Plants, friendly Dryads have +2 Initiative, and each different type of Plant in the allied army provides +4 Defense to the Faun), Elemental Power
Their damage has been boosted and now has its type different for melee vs ranged and in the process has switched to actually having the melee attack be identical in base damage to the ranged attack, Fatigue can't hit as large of stacks (It's lost 25% of its previous value), Nightmare's minimum damage went up by 2, Forest Spirit Spirit of the Wood has been completely overhauled aside from a thematic similarity, they've unfortunately lost 2 Initiative (ouch), and of course they've picked up Elemental Power. The overall result is that Fauns are much more useful as damage dealers, rather than being supporting units that make some vague attempts at dealing damage.
They're still overall oriented toward being support pieces, but they're not nearly as disappointing when it comes to dishing out damage, is the point. Underground combat is also a bit more unusual in Warriors of the North than in Armored Princess, so Fears Darkness is somewhat less impairing of a trait, and there's more plants and overall plants are better in Warriors of the North so Fauns specifically supporting plants is a specialty more worthwhile to explore.
They're still painfully fragile, but even this is helped some by the fact that one Valkyrie Ability can periodically undo casualties from units up to Level 3, and whaddya know Fauns are Level 2. Arranging to use said Valkyrie Ability in preparation of a ranged-heavy fight or something else likely to cost you a lot of Fauns is one way to minimize the problems with their casualties.
It's worth pointing out that with Elemental Power bugged, almost 2/3rds of the time Fauns will have +1 Initiative and Poison resistance. You shouldn't assume it'll happen, but most of the time it's what they'll have. (Which means the 2 Initiative they lost between games is really more like 1) Conversely, they're on average effectively even more frail than they seem, since they can't get Earth to boost their durability the way other Elves can...

Sun Fairy
Level: 2
Hiring Cost: 25
Leadership: 17
Attack/Defense: 8 / 6
Initiative/Speed: 6 / 4
Health: 10
Damage: 1-3 Magic
Resistances: 25% Fire
Talents: Mana Source (Charge: 1. A single target ally is granted +10 Defense for 5 turns, with the duration being lowered each time the unit takes damage and 5 Mana being granted to the owning Hero when this happens. Can't be cast on units immune to magic)
Abilities: Soars, No Retaliation, Fire Protection (25% Fire resistance), Firefly (Melee attacks have a 30% chance of Blinding the target for 2 turns), Creature of Light (Allied Paladins, Unicorns, Frost Unicorns, and Black Unicorns get +1 Morale), Elemental Power
One of two new Elves in Ice and Fire. They're a third variation on the basic fairy archetype, with a minor fire theme, probably in part to help contrast Elves against the new Snow Elves, tie into that whole 'Ice and Fire' name.
On the other hand, they're actually content lifted from Red Sands, so maybe not. The Red Sands version got to cast Divine Armor instead of Magic Spring, though. I'm not sure which one I prefer, and admittedly the point is complicated by the two games being rather different. In any event the Sun Fairy is useful for Mana supplementation in Ice and Fire.
Probably my biggest frustration with Sun Fairies is that they do Magic damage instead of Fire damage. It's horribly counter-intuitive and it's a notable strike against their utility, making their primary draws compared to Lake and Forest Fairies the low chance of inflicting Blind in melee and their Talent being Mana Source. Creature of Light isn't bad, but it's not like Sun Fairies are especially synergistic with any of those units. And this is kind of the worst game in the series to be inflicting Blind in, due to how many multi-target Rage effects you've got, how powerful Rage is, and how multiple Rage attacks eventually have high odds of inflicting Freeze or are guaranteed to inflict Burn and thus shortening the Blind duration because of the damage over time immediately clearing it.
You'll only rarely fight them, and you can basically assume they're going to waste a turn with Mana Source -just like their fellow fairies, AI Sun Fairies never move beforehand- and unless they get lucky and inflict Blind with their melee they're... not interesting. Indeed, they tend to be notably less problematic than the other fairies, which have Health equal to or greater than their Leadership while the Sun Fairy has... a little under 60% of their Leadership in Health. So Sun Fairies die fast compared to the other fairies. They also have clearly worse damage than Forest Fairies, with the same Damage per head (But just under twice he Leadership required) and only 4 more Attack, which is like 12% more damage or something.
So actually Sun Fairies are kind of just trash units unless they manage to trigger Firefly. Which is... only 30% odds per hit.
It's really unfortunate and I desperately wish they at least did Fire damage so they'd have a niche compared against the other fairies.
One more way Sun Fairies are screwed over is that Druids don't actually boost their Morale! Just one more reason to not use Sun Fairies...

Avenger
Level: 4
Hiring Cost: 1200
Leadership: 200
Attack/Defense: 24 / 22
Initiative/Speed: 6 / 2
Health: 130
Damage (Ranged): 12-16 Physical
Damage (Melee): 7 Physical
Resistances: 10% Poison
, 15% Magic
Talents: Tranquilizer (Charges: 2. Ranged attack against a single target that does 11-14 Poison
damage. If the target is below Level 5 and isn't Undead, a Plant, or inorganic, it also falls asleep for 2 turns), Precision (Charge: 1. All allied ranged units do 20% more damage with their base attacks for 5 turns)
Abilities: Archer, Sniper, Night Vision (+50% Attack at night and/or underground), Bow Master (Allied bow-wielding units have +5 to Attack and crit chance), Revenge (When attacking a unit, the Avenger Pain Mirror's the target at a rate of 10%, in addition to normal damage), Poison Protection (10% Poison resistance), Magic Protection (15% Magic resistance), Elemental Power
Precision affects the same list as the Spell Precision, which is to say most units with a ranged attack. So Avengers are a very nice support for a ranged-focused army. Do keep in mind that Talent Precision only affects the base attacks, not Talents; if you're expecting to have every ranged unit busy using Talents for the turn, Precision should probably wait until later. Or you should cast the Spell version instead, possibly, as it does affect Talents. Conversely, it should be pointed out Avenger Precision does affect the melee attacks of ranged units. Yes, really. Don't think too hard on it.
Revenge makes Avengers particularly synergistic with summon spam strategies, eg using Royal Thorns to provide meatshields, and means that optimizing for damage on an Avenger actually means trying to hit whatever enemy has previously done damage. 10% Pain Mirror is admittedly fairly weak (It doesn't scale with your Intellect), especially when you consider that Pain Mirror only goes off 'real' damage done and not on the damage roll per se -so for example enemies breaking Ice Spikes will take only 1 damage from Revenge, no matter how many thousands of damage they rolled. But it's still there, still a cool idea, and the damage can add up.
Note that Revenge can't trigger on melee attacks, but absolutely can trigger on Tranquilizer and even Dragon Arrows. Though it should be pointed out their Dragon Arrows are slightly weaker than intended, with a base damage of 12-15; one less maximum damage than they're supposed to do. It doesn't matter much, mind, but whoops.
Also note that Avengers, in spite of being a variation on the Elf-the-unit/Ranger model, do not have No Melee Penalty. They have so many Abilities it's easy to overlook that it's not in that list and just assume they do, but nope. They really don't like being in melee, in fact.
Avengers themselves are, you guessed it, content lifted from Red Sands. Their numbers have been tweaked, but mostly they're the same unit as in Red Sands.
Tranquilizer is by far the big thing Avengers have going for them, as inflicting Sleep 100% reliably at range for 2 turns is amazing. This comes with the caveat that Undead are very much a default foe for a lot of the game and they're all immune to the Sleep part and heavily resistant to Poison damage, but there's still plenty of fights to take advantage in and seriously being able to just remove a target from consideration for two turns is priceless. Remember: while bears instantly wake up when hurt if they induced Sleep via Hibernation, Sleep is actually normally unaffected by damage. So you can put an enemy to Sleep and start shredding them right away!
Precision is nice -I like to use it on Luck Rune-provided turns, in part because it ensures I'm already through the first turn of Talent spam- particularly if you're going whole-hog on ranged units because you found the Dragon's Quiver or something but it's more a nice little bonus than anything else. Do note, however, that it suffers from the same error as Flaming Heart on Pyromages, so if you're playing a Viking and have at least Rank 2 of Steadfast Norse, Precision will only last 4 turns rather than 5.
Enemy Avengers should, of course, be priority targets. The AI isn't particularly intelligent with its Tranquilizer use, but it mostly doesn't need to be! Just having any unit out of the fight is a problem, even if some might be worse problems than others.
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I really like Elves in Warriors of the North. They could still use some tuning, but I really think Warriors of the North is the best-designed version of Elves in the series.
Next time, Orcs are on the march again.
See you then.