I still don't understand why people think that there's a conflict between balance and emulating the novels.
+1
Step 1: Create the mechanics for the power. Capture to the best degree possible the flavor of the novels.
Step 2: Assign a refresh cost that reflects to best degree possible the overall utility of the power relative to other powers.
Poof. Feel of the novels plus balance. Simple, right? Ok, I admit, it's easier said than done, of course, but its worthwhile to strive for.
Possession is a 3 Refresh upgrade to a 2 Refresh Power. And its actual effects are so vague that it's almost impossible to say how strong it is.
Actually, it's worse than that, because it
also require Spirit Form [-3] or Gaseous Form [-3] (or possibly a similar custom power). So its actually a 3 refresh upgrade to
5 refresh worth of powers!
Other notes:
A significant balancing feature of Evocation is that every use requires a mental stress (or more), which means that you have lots of flexibility and power, but only a few times per scene. You can 'buy' a few more uses with consequences, assuming you don't have other needs for them. Claws, by contrast, grant a much lower level benefit -- that can be used every exchange of every battle indefinitely. Much less flexibility, but 'always on'.
Being able to use consequences to 'soak' an extra
five shifts worth of damage per scene doesn't seem particularly useless to me, either. (Baseline is a mild every other scene or an average of one shift per scene; Inhuman Recovery is two milds per scene and a moderate every other scene, or an average of six shifts per scene.) And that doesn't even consider the significant boost to recovery of serious consequences. Not as flashy as Evocation, surely, but certainly valuable.