Io, Attendant of Blood

Lifelink
Creatures you control with lifelink have +1/+0.
If your life total would be reduced to 0 or less,
instead sacrifice this creature and your life total becomes 5.
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.)