Essence Hunter

Undying (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 Essence Hunter would have one or more +1/+1 counters put on it, put that many
-1/-1 counters on it instead. Whenever one or more -1/-1 counters are put on Essence Hunter,
add one mana of any color to your mana pool.
"To find the light within darkness is the key to immortality."