Carcette, Arkay's Authority

At the beginning of your end step, for each player, put a +1/+1 counter on up to one target creature that player controls.

Each creature with one or more counters on it can't attack you or planeswalkers you control unless its controller pays {x}, where X is the number of counters on that creature.

(Based on the card Nils, Discipline Enforcer)