TBH I would prefer that this become’s the room with the least number of pickers (not counting 0) in order to make it a reward for good play instead of just over complicating things.
Having it in the least picked room doesn’t change anything as everyone is already trying to go for the least picked rooms. You may aswell not have it.
Having it in a random room means there’s one more thing for people to consider when choosing rooms. It’s hardly complicated.
Round 1
With 20 players alive there are 6 rooms.
Room Choices:
1 - Air - All pickers become light.
2 - Luck - If this room is the majority, then one random picker will survive. If this is not the majority, then one random picker will die.
3 - Mundane - This room literally does nothing.
4 - Earth 
- A random picker becomes heavy.
5 - Evil - All pickers become cursed.
6 - Feast - All pickers gain a tangerine.
