When Dance of Many enters, create a token that's a copy of target nontoken creature.
When Dance of Many leaves the battlefield, exile the token.
When the token leaves the battlefield, sacrifice Dance of Many.
At the beginning of your upkeep, sacrifice Dance of Many unless you pay
.
If Dance of Many leaves the battlefield before its first ability has resolved, its second ability will trigger and do nothing. Then its first ability will resolve and put a token onto the battlefield. That token won't have any connection to a Dance of Many permanent, so it won't be exiled when a Dance of Many leaves the battlefield.