Vish Kal, Blood Arbiter (CMD-234) - Commander 2011
Sacrifice a creature: Put X +1/+1 counters on Vish Kal, where X is the sacrificed creature's power.
Remove all +1/+1 counters from Vish Kal: Target creature gets -1/-1 until end of turn for each +1/+1 counter removed this way.
Pickup available at Mana Market
Usually ready in 24 hours