Bloodraven, He who Whispers

Bloodraven, He who Whispers enters tapped.
{t}: Add {b} or {g} to your mana pool. Each player
puts the top card of their library into their
graveyard. If Brandon, Seer of Secrets is put into
your graveyard this way, you may sacrifice
Bloodraven, He who Whispers and put Brandon,
Seer of Secrets onto the battlefield.