Dimir headquarters

{t}: Add {c} to your mana pool.
{u}{b}, {t}: Target player puts the top three cards
of his or her library into his or her graveyard.
{2}{u}{b}, {t}, Sacrifice Dimir headquarters:
Exile traget instant or sorcery spell from its
owner's graveyard.
Copy the exiled card and cast it without paying its mana costs.