Slifer the Sky Dragon

Haste, vigilance, flying I
As an additional cost to cast Slifer the Sky
Dragon, sacrifice three creatures. This spell
can't be countered. This creature's power and
toughness are equal to the number of cards in
your hand. Whenever a creature enters the field
under your opponent's control, put two -1/-1
counters on it.
"The heavens twist and thunder roars, signaling the
coming of this ancient creature, and the dawn of
true power."