Combat Purification

Sacrifice a creature, then target opponent
sacrifices a creature with power X or less. You
put a creature token into play under your control
that is a copy of any creature that had the highest
power among all creatures sacrificed so far this
turn, except it is black and comes into play with a
-1/-1 counter.
"Ready for my sword? I think you'll find combat with
me to be the most purifying thing of all."