Death Cleanser

Deathless (When this
creature dies, if it had no -1/-1 counters on it, return it
to the battlefield with a -1/-1 counter on it. It becomes
a Zombie in addition to its other types.)
When Death Cleanser enters the battlefield, if
has no -1/-1 counters on it, then you may remove a
-1/-1 counter from target creature.