Imagine raging, and whirlwind and crippling blow a group of enemies and knocking them down with battering ram, then skin grafting and AOE critting AGAIN. That's a recipe for wrecking everything.
It doesn't restore your AP, so you'd have to wait until the next turn.
Alternatively, you could just use other skills from another tree instead of re-using the same ones.
Sure, it takes another turn (unless you can get warlord to proc a bunch). But there's definitely times when the best one or two skills in a situation are on cooldown. Whirlwind + crippling blow are pretty much the best skills to use if you have 3+ enemies around you. Even if you're a hybrid with a bunch of other skills to play with. And especially if you're NOT a hybrid, with a fairly limited pool of skills. Between Polymorph + Warfare, there really aren't that many offensive AOE skills.
How is it balanced that I only need to invest 1 point into Polymorph to get a skill that effectively DOUBLES my damage output?
Take any build you want. Add Skin Graft to it. Your build is twice as good.
This is blatantly untrue.
This assumes all damage is done via abilities (ignoring weapon attacks) and assumes that users are generating AP faster than they are generating cooldowns, which is also particularly untrue after a few levels. There is no way any build doubles its damage from including Skin Graft, not even for just 1 turn of simulation. It's not like Skin Graft grants you extra AP to actually use all of those CDs.
Also, this claim ignores the drawback of losing all armor from casting Skin Graft. The extra CDs may seem hollow if you are CCd on the next enemy turn.
Double damage might be a bit of a stretch, but it could be a significant boost in damage. Skills tend to deal more damage than weapon attacks, and certain skills are especially potent. Two 3-4 enemy hitting ricochets is a lot more damage than one ricochet plus a standard attack.
Really, this is all such moot discussion with the minimal limitations on what skills you can learn. With Skin Graft as a 3+ polymorph needed skill, it will remain a great skill, but not one that you can throw into any build for instant massive utility. We really need to see proper limitations on skills. Even 2 points needed for certain skills would be a good start.
The armor loss is a significant downside, but again, the skill is best used as a finisher, when your armor is already low or gone or the most dangerous enemies are cc'd.
