[Phantasm]

Originally Posted by Hellboy

Keeping with the above concepts, is there a way to charge ongoing FP costs for staying in altered form?

Like "I can only stay Super Saiyen so long" or something.

I remember there was a lot of examples like this but can't really remember particulars, just something where it's exhausting to be in an altered form.

See my post just prior to yours. :)

Originally Posted by Hellboy

Suddenly remembering 'Monster Girl' from the Invincible series. Or similarly, this one girl Loco in Marchen Awakens Romance...

Is there a way to link either to a transformation or a supernatural ability that the cost of using it is that it de-ages you?

This is a great advantage if you have a lot of other stuff to rely on, but in the case of Monster Girl and Loco began as young adults and were having to regress to being prepubescent/toddler and risking de-aging themselves out of existence in the course of fighting battles. When it comes to that it's sort of like a disadvantage, particularly as stat penalties come up for losing size.

Maybe in that case the ability itself would not be a disadvantage but its use could be monitored and result in advantages (losing age disadvantages if you begin elderly and reach your prime) or disadvantages (gaining youth disadvantages if you begin in prime and become undeveloped) as use accrues.

Both the MG/Loco examples also had compensations for that. MG tried using power armor to fight instead of tranforming, while Loco (albeit this might have been an anime filler only arc, not something from the manga) managed to find a new cursed charm which didn't steal her age to fuel it, I think it had something to do with harnessing animal powers.

I'll be honest, I don't know about age-regression the longer you use powers; usually I've seen powers (usually speedster types) that age you because they've sped up your metabolism and the more you use them the faster you age until you keel over of old age.