Mesmerizing Butterfly

Hatch {u} (Whenever you put this card from your
library into the graveyard, you may pay {u}. If you
do, then put this creature from the graveyard onto the battlefield.)
flying
Whenever this creature attacks or blocks,
creatures your opponents control get -1/-0 until
end turn. Whenever this creature deals combat
damage to a player, draw a card, then put the top
card of your library into your graveyard.