Okay, I don't know if Dark Urge was added last and properly tested, but the rewards you receive for committing to your urges are absolute garbage, with one exception.
Deathstalker mantle is fantastic on rogue/assassin, as they can hit-and-run in every fight basically. However,
is simply put one of the biggest letdowns in game.
A Moon Druid is stronger than it is and Elemental Wildshape just leaves it in the dust, even with the current issues it has got. Owlbear has got multiattack, leap, rage, etc. What does *spoiler* get?
-98 HP, 16 AC (considering we get it in ACT 2, where 20 AC is pretty normal for a martial), it sucks
-No saving throws (worse than wildshape)
-No condition immunities (frightened, paralysed, prone, etc)
-No magic items bonuses (similar to wildshape)
-Your mental scores get replaced (worse than wildshape most of the time, unless you have got 8 in charisma, wis and int somehow). Supposedly it's a bug, but I am writing it down anyway.
Considering what we have to do to get this form, this suffers from the same problems as being evil in BG 3, it loses content for lacklustre rewards.
This thing should be able to go toe to toe with a boss (maybe not the final boss or act 3 bosses) by itself, but it it's basically nothing more but a glorified healtbar.
In fact, here is an idea how to make going evil tempting, similar to how Baldur's Gate 2 did it:
In BG 2, you had your own personal space, similar to a camp. There you could take trials, which gave you rewards based on your choices (good and bad).
However, in Baldur's Gate 3 I would make it similar to Mind Flayer Skill Tree.
You start at the bottom, similar to a tree, something like this:
0 <- Tier 5
0-0-0-0 <- Tier 4
0-0-0 <- Tier 3
0-0 <- Tier 2
0 <- You start here, by commiting your first urge. Tier 1
Let's split it into tiers:
Tier 1 - Deathstalker Mantle
Tier 2 - Auto crit on demand, similar to Luck of the Far Realms or Executioner's Ring + Making your enemies bleed on a hit of 18 and abve
Tier 3 -
The Slayer Form, but stronger
+ 2 crits/something else + extra damage to bleeding targets (make those benefits carry over to both Wildshape and *spoiler*)
Tier 4 -
The Ravager, aka a stronger Slayer
+ even stronger abilities, you get the idea
Tier 5 - you become the Big Bad of the game and almost unstoppable monster.
Of course, it isn't just free power boost, like mind flayer powers are right now. The more you use these power, the more you risk losing control and making it worse:
-Higher DC to resist, less if you refuse your urge all the the time
-Locking out certain endings, as you basically fall into darkness more and more
-More Scenes like the one in Act 1, where you kill an innocent NPC, without being able to resist. I can think of a quite a few innocents that could die to the Dark Urge
-Your companions being terrified of you and leaving if you go to far. With each tier, making it more likely to happen.
-If you reach tier 5, everyone auto-leaves you, with maybe 1 exception.
There, Dark Urge is now tempting, powerful and oh so juicy for those paladin builds. What do you think?