Tartarus

Tartarus enters the battlefield tapped unless you
have three or more instants and/or sorceries in
your graveyard.
{t}: Add {u} or {b} to your mana pool.
"The world likens this place to something out of a
Greek myth calling it Tartarus. That's the name of the
underworld prison where kings and Titans where
punish. Escaping would be a struggle even for me."
- All for One.