Bloodthirster of Khorne

You may pay {b}{r}{g} and sacrifice a Chaos
Champion rather than pay Bloodthirster of
Khorne's mana cost
Haste, Trample, Bloodthirst 4, Flying
Bloodthirster of Khorne must attack if able.
Whenever a creature dealt damage by Bloodthirster dies, put a +1/+1 counter on it.
At the beginning of your end step, if the
Bloodthirster did not attack, put a -1/-1
counter on it.