Kadha of the Slaughter

Changeling, first strike, haste
At the beginning of your upkeep, create a 0/1
green Sheep creature token.
Sacrifice a creature: Add {u}{b}{r} to your mana
pool. Spend this mana only to cast instant
and/or sorcery spells.
Whenever you sacrifice a creature, Kadha of the
Slaughter gets +1/+0 until end of turn.