There doesnt seem to be any more ordinary skills except those you get at the start.
And a lot of normal magic skills from the previous game now serve as Source skills. While this game is supposed to be about Source powered Godwoken so having some spells that feel a bit epic fits with that. And using them a lot.
Most of the ones i tried dont feel too strong or game breaking.
There is a few obviously OP examples but that can be tweaked and nerfed.
I havent tried using source vampirism in combat so i cant remember or say if it has some Ap cost, but if the goal is to make source points less easily available, then source vampirism AP cost can be raised to nerf it.
As for bosses, im sure they will have their own source spells and defenses against ours.