Darkened Nebrie

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.)
Whenever Darkened Nebrie enters the battlefield
or deals combat damage to a player, you may pay
life equal to its power. If you do, proliferate.
(Choose any number of permanents and/or players,
then give each another counter of each kind already
there.)