Sky Dragon of Osiris

This spell can't be countered
Flying, hexproof
Sky Dragon of Osiris' power and toughness is
equal to twice the number of cards in its
controller's hand.
Whenever a creature enters the battlefield under
an oponnent's control, put four -1/-1 counters on
that creature.
If Sky Dragon of Osiris was put into play from a graveyard, it gains haste. Sacrifice it at the
beggining of the end step.