Abilities: Magic Resistance (25% Magic resist), Horn of Light (Adds Magical damage against Undead and Demons), Tolerance (No Morale penalty from allied Undead)
All this similarity includes that the in-game presentation is misleading, suggesting they do mixed Physical/Magical damage when this is only true against Demons and Undead. This extends to the claimed +30% damage boost being close but not quite correct -they gain 4-7 Magic damage, which is actually exactly 33% more damage being added.
Dryad
Level: 2
Hiring Cost: 50
Leadership: 20
Attack/Defense: 4 / 12
Initiative/Speed: 4 / 3
Health: 25
Damage: 1-4 Magical
Resistances: Generic.
Talents: Summon Thorns (Reload: 2. Summons into an adjacent tile either Thorn Warriors or Thorn Hunters, with a total of Leadership of 8-10 per summoning Dryad), Elven Song (Charge: 1. Allied Elves gain +3 Initiative for 5 turns), Lullaby (Reload: 3. All enemy creatures below Level 4 that aren't immune to mental effects fall asleep for 2 turns)
Abilities: Soaring, No retaliation, Beauty (30% chance to dodge attacks from male humanoids), Charm (Melee attacks have a 20% chance of charming enemy male humanoids for 2 turns), Tree Fairy (+1 Morale for Plants)
Charm is additionally bounded by Leadership; a Dryad stack can't take control of an enemy stack whose Leadership is higher than the Dryad stack's. It's pretty easy to just not see it trigger as a result, even if you use Dryads pretty heavily.
Dryads are ultimately the biggest reason I tend to struggle to justify using Sprites or Lake Fairies. If I want a soaring melee girl Elf who has No Retaliation and does Magic damage in melee and readily costs me Gold when hit, Dryads trade away some Speed in exchange for unlimited cannon fodder summoning (Making it easier to control enemies to maximize the Dryad's own damage output and minimize the odds of taking damage), the ability to just flatly shut down entire armies for two turns, and the potential to just randomly take zero damage when something does get into melee with them (Admittedly assuming the thing in question is a male humanoid), which just seems like a really amazing deal. This isn't even counting that Dryads passively improve Plants (Not their own summoned Thorns, unfortunately), nor am I counting Elven Song or Charm as pros for this comparison. If you've got Anga's Ruby, the comparison becomes particularly absurd; 3 Speed vs 5 Speed on Lake Fairies genuinely lets Lake Fairies eg kite enemies Dryads just plain cannot without convenient terrain formations. Anga's Ruby turns that into 6 Speed vs 8 Speed, and while 8 Speed is amusing it's usually not really any more useful than 6 Speed.
As enemies, Dryads are hampered primarily by the AI not understanding how to use them. They can be obnoxious if your army is made entirely of male humanoids and the RNG just hates you, but they tend to plant Thorns when they should be attacking, open the battle with Elven Song instead of doing anything to hurt you in the here and now, using Lullaby when they should be summoning Thorns... and in general summoners tend to be more helpful in the player's hands and detrimental in the AI's hands. You summoning Thorns stalls a melee attacker for at least a turn while they kill the stack, and even in Hero fights can distract the enemy Hero from zapping something that costs you Gold when it takes casualties. The enemy summoning Thorns can become an opening where you drop a Kamikaze on the newly-summoned Thorns, instantly kill them with a stack of your own (Or, if you're a Mage, a follow-up Fireball or Fire Rain), and watch the fireworks as the Thorns detonate for massive damage to the enemies clustered nearby. (The summoning Dryads, if nothing else) Or the AI summoning blocks off a teammate you were actually worried about, delaying it more than a turn because it's not going to crush this summon like it would if you dropped a tiny summoned stack in its way.
One thing worth pointing out is that Dryads are one of a handful of units in The Legend to have more HP than Leadership. This makes them surprisingly durable even when you aren't running into Beauty causing Misses, and then they have No Retaliation and multiple supporting abilities, allowing them to contribute quite a lot without risking taking hits. This is part of why they make for such good player units, and also something to keep in mind when estimating whether your army can take on a given Elven battlegroup or not: if the group is rated as larger than you, and it's mostly Dryads, you may find yourself struggling even though other Elven battlegroups of the same rating aren't so much of a problem.
Overall, I really like Dryads as a unit, even with the moderate amount of jank to them.
Treant
Level: 4
Hiring Cost: 800
Leadership: 260
Attack/Defense: 30 / 36
Initiative/Speed: 2 / 2
Health: 200
Damage: 25-30 Physical
Resistances: 10% Physical

, 50% Poison

,
-100% Fire

Talents: Running (Charge: 1. +2 Action Points), Wasp Swarm (Reload: 2. Ranged attack that does 12-15 Physical

damage and 12-15 Poison

damage per Treant, with an effective range of 4. This includes that it can't be activated if an enemy is adjacent)
Abilities: Plant (-100% resistance to Fire, +50% resistance to Poison, immunity to mental effects, assorted secondary implications)
Treants are the Elven version of a generic 2-Speed Running melee unit. Where Dwarves-the-unit are doing nothing useful until they hit the enemy's lines, Treants are harassing the enemy on the way in with attacks the enemy can't really do anything about, which are in fact only very slightly worse on average than their basic melee attack is. If it weren't for Wasp Swarm's limited effective range, you could honestly basically use Treants as a serviceable ranged attacker that doesn't lose most of its utility when an enemy gets into melee with it. As-is, they're useful to charge enemy lines while making attacks of opportunity and can even to an extent kite slow-moving enemy melee. (Or just plain kite if you bother to give them some kind of Speed boosting, such as Haste) Yes, you can kite people with a tree. The Legend is awesome like that.
Their primary flaw as a melee unit in player hands is that being a Plant bars them from eg Resurrection. This is particularly relevant/frustrating because the game is designed so that it's more-or-less guaranteed that you've gotten access to Resurrection by the time the game is willing to let you field Treants. In most other respects, being a Plant is actually very useful, making them immune to various hostile effects, giving them high Poison resistance, etc, with the Fire weakness only erratically relevant (There are very few units that can do Fire damage. It's primarily a Spell-relevant damage type) and throwing in benefits like Dryads bolstering their effectiveness. They're further cramped by the fact that the late game is the point in the game where it becomes increasingly normal for the player to be taking on battlegroups whose total Leadership is far higher than their own. Being able to tank hits and dish out good damage is just not so useful if you're being attacked by a stack that's four times your Leadership. You really need 'autoscaling' effects of some kind to stay relevant.
As enemies, Treants are unusually class-dependent. For the Mage, they tend to be easy mode; time to drop Fireballs/Fire Rains to instantly wipe out a sizable fraction of the enemy army! For the Warrior and Paladin, they're basically generic 2-Speed Running melee that takes even longer to reach your front lines but harasses you with damage you can't block outside of actually locking off their Talent access or the like, making them more annoying than eg Zombies. Their nature as a Plant has fairly low relevance on the army end of things when they're hostile; few Fire damage units are particularly useful for the player, particularly at actually dealing out damage, and the biggest protection being a Plant provides -immunity to mental effects- is very much old hat, what with every random Undead unit having it and a variety of other units -such as Cyclops- getting that protection as well. Unless you've, like, been relying on Heal-nuking Undead cases, you've probably developed a solid battle plan that works more or less the same with Treants, other than them flinging ranged damage at you.
Ancient Treant
Level: 5
Hiring Cost: 3600
Leadership: 1200
Attack/Defense: 40 / 50
Initiative/Speed: 1 / 1
Health: 1000
Damage: 100-140 Physical
Resistances: 10% Physical

, 50% Poison

,
-100% Fire

Talents: Wasp Swarm (Charge: 1. Ranged attack on a single enemy that does 50-90 Physical

damage and 50-90 Poison

damage, each per Ancient Treant, with an effective range of 4. This includes that it can't be activated if an enemy is adjacent), Summon Wasps (Reload: 1. Recharges Wasp Swarm)
Abilities: Plant (-100% resistance to Fire, +50% resistance to Poison, immunity to mental effects, assorted secondary implications)
Unlike a lot of the 'bigger, meaner version of some other unit' units in the game, the Ancient Treant really isn't the same thing as a Treant. Its ranged attack requires active effort to reload it, and Ancient Treants only get 1 Action Point on their own, meaning that if you don't support them with Haste or something of the sort, they're choosing between moving around vs keeping up the ranged damage. As such, without speed support of some kind they're basically an immobile ranged unit that happens to be shockingly hard to kill and perfectly able to defend itself in melee. Even there they differ from Treants, as an Ancient Treant's Wasp Swarm is better at dishing out damage than their melee attack rather than very slightly worse, the only caveat being Ancient Treants are worse at arranging to get into effective range.
That said, a lot of what I said about Treants still applies. Mages tend to be happy to see them in battlegroups due to the Fire weakness, Ancient Treants show up at a point in the game that highlights a number of their problems (Though Ancient Treants are much more appreciative of the fact that you probably have basically every Spell that could possibly benefit them), etc.
One point worth noting regarding hostile Ancient Treants is that the AI will usually elect to move next to an enemy if it can, instead of firing off a Wasp Swarm or reloading Wasp Swarm. This can be used to basically ignore an Ancient Treant for a few turns by simple virtue of constantly keeping just barely out of its reach while it fruitlessly pursues you turn after turn.
Ancient Treants are also not as hard to kill as one might hope, given their overall role, unfortunately. This is, again, exacerbated by how late in the game they are -stack sizes are high enough by that point that basically anything is going to suffer a casualty if it's hit by a non-resisted attack- but they really are just not as impressive as their statline might make you think.
Thankfully, later games bolster them quite significantly.
Elf
Level: 3
Hiring Cost: 270
Leadership: 80
Attack/Defense: 21 / 15
Initiative/Speed: 5 / 2
Health: 50
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
While Elves have No Melee Penalty, they can't use Double Shot if a unit is adjacent to them. As such, they still don't like having units in their face, even aside the risk of being retaliated against.
Also, am I the only one that sees Link of Ocarina of Time when looking at their face? It's more pronounced with Hunters, but even with Elves that's where my mind goes, and that's not typical of elves I see in other media.
Anyway, Elves are basically your generic apex archer unit. They're... once again, hampered by how late in the game they show up. For example, you've probably got Dragon Arrows, and in fact probably got it ages ago, which includes as one of its (absurd) benefits unlimited effective range. If you're really wanting a powerful Sniper-esque archer unit, good ol' Bowmen backed by Dragon Arrows will actually tend to fill that exact role better, while also throwing in access to Ice Arrow and, if you've taken Training 2, Flaming Arrow, offering utility effects Elves just plain cannot match. Or maybe you're running Skeleton Archers, in which case they've got Poison Arrow (Letting them punch holes in certain Physically resistant units, even without needing Dragon Arrows) and Black Arrow (Again, punch holes in Physically resistant units, while throwing in purging a positive effect from enemies where relevant) in addition to getting to supplant Elves via Dragon Arrow. Bowmen are less picky about their allies than Elves, and the problems with Skeleton Archer racial compatibility may well be incidentally wiped away (If you went straight for Inquisition, you got Tolerance 1 by definition), leaving basically the only advantages Elves have being 'No Melee Penalty' (But you still don't want units in melee with them...) and 'doesn't need Dragon Arrows to snipe', which is a pretty minor caveat given how utterly ridiculous Dragon Arrows is.
The fact that Hunters exist and overall tend to perform better doesn't help either.
As enemies, Elves are rather more meaningful. Pinning them with a melee unit still ends up hurting quite a bit, ignoring them to focus on nearby melee enemies hurts because they're Snipers, and they're high enough Level you might not have some of the easy answers actually able to affect them. (eg Blind)
Hunter
Level: 4
Hiring Cost: 700
Leadership: 150
Attack/Defense: 27 / 18
Initiative/Speed: 6 / 2
Health: 90
Damage (Standard): 8-10 Physical

Damage (Anti-beast ranged): 12-15 Physical
Resistances: Generic
Talents: None
Abilities: Archer, Sniper (Unlimited range), No Melee Penalty, Hunter (Calls the anti-beast attack when firing on a relevant target at range)
It's an Elf, only the Double Shot damage is its base damage... but their Leadership is nearly twice as high... ah, but that basically means an equivalent-size Elf stack hits twice as hard once every three turns and slightly worse on the other turns, and Hunters are also less bothered by units getting in their face.
Still, Hunters are fairly boring units, and almost everything I said about Elves applies in terms of eg 'shows up so late in the game that the game design undermines their utility'. Even their Hunter Ability is hurt by this, as the animals that qualify show up much more heavily before you're liable to have Hunter access!
Also note that since their anti-beast bonus damage is implemented as a separate attack, they don't get +50% damage against beasts when using Dragon Arrows. So that's awkward.
Druid
Level: 3
Hiring Cost: 240
Leadership: 110
Attack/Defense: 16 / 22
Initiative/Speed: 2 / 2
Health: 48
Damage (Ranged): 4-8 Magic

Damage (Melee): 2-4 Physical
Resistances: 25% Magic
Talents: Summon Bear (Charge: 1. Summons a stack of Bears or Ancient Bears, whose stack size is determined by having their Health be 15-20 per Druid in the casting stack), Training (Charge: 1. Steals a target animal stack whose Level is below 4 and whose Leadership total is 88 or less per Druid in the casting stack. This control lasts for 2 turns)
Abilities: Power of 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), Harmony Aura (+1 to Morale for allied Elves)
Druids are a surprisingly underwhelming unit.
One of their problems is they're strangely slow to act. 2/2 on Initiative and Speed is worse than the vast majority of units in the game, and a sizable portion of the units they do beat in turn order are, themselves, fairly dubious units. (eg Zombies, Peasants) This is particularly problematic on a ranged unit (Because whichever ranged units go first can immediately hurt the enemy ranged units to reduce the damage they take in turn, where a melee unit that's low on turn order isn't any worse off in the first turn or two than one that's high in turn order, and indeed a melee unit with awful Initiative but insane Speed will actually start putting work in before one that's the reverse), and especially in the context of their ranged splash damage attack. (As enemy units will largely have broken up their formation before the Druid gets a chance to hit them with it)
Speaking of the ranged splash attack, their damage is fairly poor for their Leadership and in practice you'll rarely hit more than two, sometimes three units at a time, both in general and due to the aforementioned turn order problem. The late game (Where you actually have access to Druids) is also fairly heavily populated by units with at least moderate Magic resistance (eg Dragons, Unicorns), making their lackluster damage go even less far.
The ability to summon (Ancient) Bears works out as somewhere between 25%-33% of a Bear per Druid, when Bears are slightly over half the Leadership per head compared to Druids. So in practice your Druids are summoning a stack of Bears whose Leadership is in the vicinity of 15% of the Druid stack's Leadership. That's a really low rate, overall -if you paid attention earlier, Dryads summon 40-50% of their Leadership in Thorns, and those Thorns can then summon more Thorns, not to mention the Dryad's summoning Talent is reloading. Other summoners we'll see later are pretty much universally better than the Druid at summoning, and while some of them have caveats attached (eg Necromancers need a corpse to work with) others do not (eg Demons, the aforementioned Dryads) and even the ones with caveats are usually pretty decent units in their own right, with the summoning being basically a bonus.
While Bears that are summoned maximizes the positives of Bears while minimizing their problems, at 15% of your Leadership they're depressingly likely to be instantly killed, or even 'merely' slashed to nearly nothing. Arguably your Druids are usually going to be better off using their (depressingly weak) ranged attack instead of bothering to summon Bears, since the Bears are unlikely to do any damage.
They can steal enemy units wholesale, but only if those units are both considered to be 'animals' (This is a surprisingly limited list, for instance excluding all the spiders and Devilfish) and are also somewhere below the Druid stack's own size. As with several other Elven units, the fact that they show up late in the game hampers the issue -anything you can steal likely involved you ripping half the stack apart first, and that's assuming your Druids didn't suffer any casualties while you were arranging this to happen at all. (Not even touching on how animals are fairly rare in the late game!) One of the few exceptions is, ironically, that of being basically guaranteed to be able to steal newly-summoned Bears enemy Druids made... which is amusing, but in practice the enemy Druids will probably just steal them back. (This is totally a thing that can happen!)
Harmony Aura seems like a tempting reason to take them along, just for the passive boost to other Elves, but Morale's effect isn't that huge and it has diminishing returns in practice. Having 4 other units have 10% more Attack is neat, until you realize that if you're doing that the Druids are actually only increasing the Attack by about 9% (Because that's roughly what going from 110% to 120% works out to) and more importantly realize that Druids are sufficiently poor as units that you'd probably have your army's performance overall higher if you replaced the Druids with some other Elf, or possibly even a non-Elf!
Even as enemies, Druids are surprisingly lackluster. Their already poor damage gets made worse by the AI tending to have them just stand wherever they are, like some kind of turret, instead of trying to get into effective range. The Bear stacks they summon are so small that even the fact that the player will increasingly face oversized enemy stacks won't lead to the Bear stacks being more than a momentary nuisance. I skipped over it when talking about using them because for the player it's usually not too much of a problem for a ranged unit to have this issue, but Druids are also quite poor at the Leadership-to-HP ratio, their HP being less than 50% of their Leadership. Most units whose HP is less than 50% of their Leadership are somewhere over 1000 Leadership, not a little over 100, and make up for it with powerful qualities (eg Archdemons having Teleportation and purging all negative effects on themselves every turn for free) and often throw in unannounced minor-to-modest resistances. (eg Black Dragons have 15% Physical resistance, in spite of lacking an Ability to explicitly justify this degree of resistance) A Red Dragon's poor HP is misleading, because only Poison does full damage to them. A Druid's HP is exactly as bad as it looks, aside from their not-very-high resistance to Magic.
This is compounded by their poor placement in the turn order: Druid stacks are quite vulnerable to suffering huge casualties before they ever get a chance to do anything, which in turn worsens the other problems. (ie it's bad enough summoning around 15% Leadership of Bears when you're actually at full Leadership, but if your Druids are nuked to 50% by Evil Gremlins, that already-tiny Bear stack is shrunk still further)
And it's quite clear the developers agree with me, because Armored Princess drastically improves them!
But that's for later.
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Narratively, Elves are fairly interesting to me. The game likes to hint that they're not intended to be as awesome as they think of themselves as being, and even more interesting is their relationship to eg the Undead. The game doesn't exactly spell it out, but part of the reason there's some Tolerant units on the Elves is because they invented Necromancy, and indeed there's a couple of 'Books of Death' in their lands that let people go hang out in the deathlands, also made by Elves. The game doesn't make a big drama point of it being a stain on Elven pride or whatever, but it's a historical fact, and it's an unusual choice for a fantasy story of this sort. It's even thematically appropriate to connect your 'in tune with life/nature' species with themes of death.
One of the more subtle, interesting examples of subverting tropes about Elven awesomeness is that the Elves speak of themselves as being the eldest race (Which is, for reasons I've never really understood, a fairly common trope for Elves in fiction. Okay, sure, individuals are long-lived, but why does that have to correlate to the species' history stretching back to the dawn of time?), but it's made quite explicit by the plot that this is simply untrue; Orcs were made first. Elves are the first race made by the gods of the setting, but the titans were at these shenanigans first and made the Orcs earlier.
Gameplay-wise, Elves are... well, they're more interesting to me for the 'concept' end of things than the actual execution. A few too many of their units are lackluster or placed in the wrong portion of the game to be valuable for me to praise the execution. But I do like some of the things the game is trying to do. It's an interesting twist on an old staple to make Elves focused on ranged attacks, but then make almost all their ranged-capable units skilled at defending themselves in melee. (Not only that Elves-the-unit and Hunters have No Melee Penalty, but also that Treants and Ancient Treants are melee tanks that fight relatively competently at range via Talents, sustainably) Not only that, but in a lot of ways the bigger focus seems to be on being able to dish out damage without having to take it, with range advantage merely being an option; Unicorns, Black Unicorns, and Werewolf Elves in both forms are the only Elven units that have neither a ranged attack/reusable ranged Talent nor have No Retaliation.
Furthermore, while the execution could use some work... well, the very next game works on it!
Awesome.
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Next time, we cover the Orcs.