3 card kill all opponents

Sacrifice a creature: Add .

When this creature enters, it deals damage equal to its power to any target. Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

You can't get poison counters. Creatures you control can't have -1/-1 counters put on them. Creatures your opponents control lose infect.