My Forces Are Innumerable (Archenemy: Nicol Bolas) (OVER-011) - Archenemy: Nicol Bolas Schemes

(An ongoing scheme remains face up until it's abandoned.)
At the beginning of your end step, create a 3/3 black Horror creature token.
At the beginning of your opponents' end step, they may sacrifice two creatures of their choice. If they do, abandon this scheme.