Journey to Arkendale

Journey to Arkendale enters the battlefield tapped.
{t}: Add {u} or {b} to your mana pool.
{2}{t}: Add {u}{u}, {u}{b} or {b}{b} to your mana pool.
Whenever you tap Journey to Arkendale for mana, target opponent put`s the top card of
his or her library into his or her graveyard.