The Id Portrait is an interesting minor artifact that I would like to use in a campaign.
Basically, the BBEG is in the Portrait and uses the alter egos to further various plans and the PCs have to deal with those without knowing all these people are controlled by one individual.
I'm guessing the vilain is expelled after X days equal to his HD-1 when all the alter egos die, but he can just get back in the Portrait and a fresh batch of alter egos are created. If well done, dead alter egos are hidden or destroyed, this can go on for years.
Should the vilain age when in the Portrait? He will mad from the fracturing of his mind, so he won't be aware of the existence of all of his alter egos, which opens up interesting avenues.
Any advice, observations or modifications to suggest?