Rot Poison Hydra

All creatures on the battlefield have -1/-1
Whenever a creature with one or more -1/-1 counters dies. creatures you control gain infect until end of turn
Sacrifice Rot Poison hydra whenever your opponent gets a infect counter
{p/g}{p/g},{p/b},Pay 4 life and sacrifice a permeant: Return Rot Poison hydra from your graveyard to the battlefield