Sorry for the uh necro, and I'm fine if this gets deleted.
But I'm wondering about like, kinda anime class concept best I can tell. A character who is possessed, like the fluff in eberron makes Elans, except with actual interaction with the possessing critter.
I like the idea of just some kind of 'super form' that draws on some pacted/possessing spirit? Like the best example I can find is an anime, Naruto, later on.
I doubt it's really anythingt hat'd interest you, but.
I'd like it as a base class, just because someone with a headvoice and transformation and such as a base class has always interested me!
Okay, going to need more than that. Just "possession" isn't enough. Super form? Bit better, but are we talking Barbarian Rage style boost or are we talking Metamind capstone? Something the class uses for every significant fight of the day, or something they only pull out when a particular target needs murderstomped?
What subsystem? Psionics, Spells, Bardic Music/[Divine] feat shared uses for several abilities mechanic, Incarnum, Truenaming, Shadowcasting, Martial Initiating, Binding... What subsystem you want? I can work out some basic stuff for you to refine the idea further, if you give me a starting point.
Heck, I'd be down for any homebrew subsystem you can link, if you can give some level of description as to how to use it. I'd love to try working with
Remnant Casting(links to subforum it's in), which is a system of unlimited daily use powers without using actions, as it's an amazing subsystem for any Gish style setup. Due to not using actions and being unlimited daily use. Actually manages to avoid being entirely broken, interestingly enough. Although there's action economy issues, for me, in that the pure caster ones don't actually have anything to use their actions on that's able to fill the workday.
Although
Spirit Magic would work better with possession, having mechanics for the character to be screwed over by the possessing entity
and get almost unconditional massive help, I'm not at all familiar with the balance point of that subsystem. It's incomplete to the point where it doesn't even have it's spell list equivalent done, so I can only use the base mechanics and implied mechanics. Like 8 Concessions per Concession level, going by the fact that there's a d8 used for the random selection. Which means needing to make 24-40 spell-like effects to penalize the character, on top of however many Dogmas are needed to be functional.
A third homebrew subsystem to use would be
Outcasts, which have mechanics heavily rooted in transformation and alien perspectives. The mechanics are fairly simple, overall, and most of the work is class-segregated. It's really just the basic mechanics of Blemishes Learned and Readied and the currently-universal theme of "outsider" present. Not in the sense of Celestials and Fiends, but it the sense of being, well, an Outcast. Apart from typical society, whether by choice, nature or reaction.
So... What kinda subsystem do you want? I can explain any of these subsystems, including the list of first-parties at the top, to you more clearly, if you need more information.