Rakdos Shaman

Unleash (You may have this creature enter the battlefield with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)
As an additional cost to unleashing Rakdos Shaman, pay {b}{r}.
When Rakdos Shaman dies, creatures you control get +1/+0 until end of turn and creatures you don't control get -0/-1 until end of turn.