I agree some of the skills aren't too original or different from other skills in this game alone, I would like to see the suggestion someone else made about combined abilities working together. For example, Bull Horns + Wings could make a dive bomb skill (fly up and towards target, then dive the target with your horns doing a smaller aoe but more mobility and maybe extra damage). Dive bomb could also benefit from height advantage bonus (since you fly up from where you are then dive, the higher you start to more speed you gain when you dive).
If you could do that, it would make the basic, less interesting skills, a lot more interesting and you wouldn't care too much if on it's own it isn't too original.
This is a great idea. Steel Skin + Bullrush could make you have a shorter range charge that deals more damage, for a simple example. I like the idea that there would be tradeoffs for combing polymorphs in certain ways. Could even affect something like the tentacle slap. Steel Skin could similarly reduce the range of the tentacle attack, but make you steal some armor from the enemy if they have any. Things could get complicated with too many combinations, but a few would be cool.
I also think Chameleon Skin should just boost sneaking by 3 or something for 5-6 turns. That way it doesn't completely step on Walk in Shadows but instead boosts the efficacy of sneak by a lot.