Nasus, The Eater of Souls

{1}{b}{g}{w}, Sacrifice a creature: Put a +1/+1
counter on Nasus. If a nontoken Creature
was sacrificed this way, put two +1/+1 counters
on Nasus instead. Regenerate Nasus. You gain
life equal to half the power of Nasus.
If Nasus killed a creature on his own, then you
can use Nasus' ability without paying it's mana
cost and the creature that died counts as the
sacrifice creature