Slifer the Sky Dragon

Flying, Vigilance, Trample, Immunity
(You must sacrifice 3 creatures in addition to the casting cost)
* is equal to the number of cards in your hand.
When a player's creature enters the battlefield
you may have Slifer the Sky Dragon fight it.
Slifer the Sky Dragon does not die when it fights
a creature. If the creature Slifer the Sky Dragon
does not die, reduce that creature's Power/Toughness equal to Slifer the Sky Dragon.