Alvela's Incantation

Whenever you cast a spell during an opponent's
turn, you may look at the top card of your library.
If you do, put it onto the battlefield face down,
as a 2/2 black and blue raven creature token
with flying and lifelink. You may turn it face up
any time for its mana cost if it's a creature.
Sacrifice a raven: draw a card.
Alvela didn't bring her flock to the Heartlands,
because the Heartlands became her flock.