Nightsnare Bandit

Whenever a player discards a card, that
player also switches the top card of his or
her library with a random card in his or her
graveyard.
{4}: You may cast blue spells from your
graveyard this turn if {u} was spent to
activate this ability. The same is true for
black spells if {b} was spent and red
spells if {r} was spent.