Gyrus, Scourge of Jund

Gyrus enters the battlefield with a number of
1/1 counters on it equal to the amount of mana
spent to cast it.
Whenever Gyrus attacks, you may remove X
1/1 counters from it. If you do, return target
creature card with converted mana cost X to
the battlefield tapped and attacking.
Whenever a creature you control dies you may
put a 1/1 counter on Gyrus.