Bow to My Command (OE01-03★) - Archenemy: Nicol Bolas Schemes

(An ongoing scheme remains face up until it's abandoned.)
As you set this scheme in motion, choose an opponent.
Creatures the chosen player controls can't attack you or planeswalkers you control.
At the beginning of your opponents' end step, they may tap any number of untapped creatures they control with total power 8 or greater. If they do, abandon this scheme.