Orc Strike
Basic stats
Rage: 4
Rest: 2
Damage: 80-100 Physical

Lethality: 4% Physical
Does Physical

damage to a single chosen enemy. Some of this damage is percentile, in addition to the more conventional damage, but the percentile damage is still Physical

and thus modified by Physical

resistance.
Something worth explicitly mentioning: Bagyr's Blood Rage does double the percentile portion of the damage when it triggers.
Orc Strike is your archetypical basic attacking Rage move, just like so many others across the series. It's the best of the bunch; in the early game it's basically a slightly stronger Earth Blade with no anti-mage bonus or a Crushing Blow with no push, but once you get into the midgame where the raw damage fails to keep up with growing stack sizes suddenly the Lethality component ensures Orc Strike is one of your best opening moves. It's my favorite basic attacking Rage move in the series, being the only one that isn't irrelevant or pushed into a supporting role as the game advances. It can easily do 10,000+ damage to enemy stacks in the late game, with only other percentile effects able to reliably keep up.
Early on, you should be focused on getting finishing blows to rank up Lord of the Darkness, particularly as Orc Strike is your best option initially for getting finishing blows. Jealousy can't do it at all, and Necropack is more expensive and better used trying to soften multiple targets, and later in the game Orc Strike will rarely have the opportunity to get finishing blows off.
Overall, though, Orc Strike is straightforward in its utility. Really really good, but straightforward.
Damage upgrades
Damage 1: Damage: 150-170, Lethality: +1%, Rage: +3
Damage 2: Damage: 240-300, Lethality: +1%, Rage: +3
Damage 3: Damage: 400-500, Lethality: +1%, Rage: +4. Rest: +1
Damage 4: Damage: 700-900, Lethality: +1%, Rage: +4
Damage 5: Damage: 1100-1400, Lethality: +1%, Rage: +5, Rest: +1
Damage 6: Damage: 1700-2100, Lethality: +1%, Rage: +5
Max Orc Strike. It's just that good.
Lethality upgrades
Lethality 1: Lethality: +10%, Rage: +8
In conjunction with maximum damage upgrades, Orc Strike ends up with 20% Lethality, which is a quite nice amount and ensures that even in the endgame when Orc Strike's regular damage is fairly meh it's still a fantastic opening move for softening up enemies.
If you're offered this in the early-to-midgame, you might want to put it off, as 10% Lethality for +8 Rage can be a poor trade at the time. You should take it eventually, though, as it's doubling Orc Strike's final Lethality value all by itself, and in late-game battles the Lethality rating will easily account for 95% of your damage output.
Sadly, there's a second Lethality upgrade in the code that's supposed to be unlocked by having all the damage upgrades, but the check is coded wrong so you'll never see it in-game. It would add another 10% Lethality, another 16 Rage cost, and more awkwardly would add +1 to the Rest period. Still, 30% of a stack's Health instantly gone would be a really big deal late in a run, so it's unfortunate that bugginess means the option is unavailable.
Increased Control upgrades
Control 1: Rage: -10, Rest: -1
You should take it. Orc Strike is just that good.
There's actually another Increased Control upgrade in the code, but it's inaccessible because the second Lethality upgrade is inaccessible, as you can't get Orc Strike's Rest duration high enough to trigger it without that additional Rest. Oops.
Final Stats
Damage: 1700-2100 Physical

Lethality: 20%
Rage: 26
Rest: 3 (2 with sufficient ranks in Action Rage)
If it weren't for bugs, its final stats would have Lethality raised to 30% and the Rage cost raised to 32.
Still, this is very solid, the best basic attacking Rage move in the series, both from a 'playing to win' perspective and from a 'good design' perspective.
Also, I phrase Action Rage's influence on Rest as requiring 'sufficient ranks', because as we'll be seeing when we get to Might Skills, Action Rage has the unique quality that which Rage moves it affects at a given rank actually depends on your class/character. As such, I can't just say 'at Rank 1, X Rage moves get the reduction'.