Heavenly Dragon-Slifer

Flying, Hexproof, Split Second
As an additional cost to cast this spell, Sacrifice 3 creatures you control.
If Heavenly Dragon-Slifer wasn't cast, sacrifice it at the beginning of the next end step.
Heavenly Dragon-Slifer's power and toughness are equal to the number of cards in your hand.
Whenever a creature enters the battlefield under an opponent's control, put 4 -1/-1 counters on it.