Infected Marauder

When Infected Marauder enters the battlefield, you lose 3 life.
Infest 1 (Whenever a creature you control dies, you may put 1 -1/-1 counter on Infected Marauder. If you do, you gain 3 life.)
Many of those touched by the Infection drew away from society, forming small bands of contorted beings that stay together until their death.