Spirit of the Deeps

Vigilance, Trample
Whenever Spirit of the Deeps attacks, exile the
top card of each player's library. Return up to
X target nonland permanents to their owners'
hands, where X is the total converted mana
cost of cards exiled this way this turn.
{t}: Choose target card in exile. You may cast
that card this turn and you may spend mana as
though it were mana of any type to cast it.