In Persona 4 there's a world on the other side of the TV that's constantly covered in fog. In this TV world, beings called
Shadows exist. The Shadows are pretty harmless to normal people, unless you have a Persona they won't attack you.... at least until the fog lifts. Shadows go berserk when there's no fog, unfortunately for anyone trapped there the only way to fight them is with the power of Persona.
That's not even the only problem they have to face either. The minion type shadows that roam the TV World are one thing, but the much more menacing danger is from what happens when a normal person finds themselves lost in the fog. That's when someone's personal Shadow comes out to play.
A person's Shadow self will claim to be their “True Self,” but really they're only a part of you. Everything you hate about yourself, every thought or emotion you've ever denied you ever had, every suppressed impulse, everything you hide from everyone else; All of those things come out in the form of an evil yellow eyed doppleganger who absolutely hates you and can and will taunt you about your flaws where everyone will hear them.
And it gets worse if you reject them, because if you do, and everyone does, it will turn into a monster and try to kill you. If you're lucky enough to survive though, you'll have a chance to accept your Shadow and if you do it will become a
Persona, your true self in weapon form, represented in the form of a mythological figure, creature or deity.
So, what I'm trying to get at here, is that the Manor should get shrouded in fog one week, so that everyone's Shadows can come out and play with their other selves.
This would also require people figuring out what Arcana they represent, since each Shadow and Persona is represented by a specific card of the
Major Arcana. This also determines the Elemental typing and strengths and weaknesses of their Persona.
Each Persona is also part of one of four categories, Offensive, Buff/Debuff, Healbot and Scanners. Scanner Persona users are like Rise, acting like mission control for the other members of a party and scanning enemy shadows for their strengths, weaknesses and arcana to better help in a fight. Offensive can either be physical or magical and is self explanatory, as are Buff/Debuff and Healbot, though Healbots can also have buffs/debuffs and both support types can have attacks, though they don't have as many.
Of course we'd have to tone down the Shadow Selves monster forms because typically a monster form of a Shadow Self is the dungeon boss, but this would be a very interesting plot I think.