Hall of the Tyrant

Hall of the Tyrant enters the battlefield tapped. At the beginning of your upkeep, if there are 3
or fewer cards in each graveyard, sacrifice Hall of the Tyrant.
At the beginning of your upkeep, each opponent may return a permanent with converted mana cost 3 or less from their graveyard to the battlefield.
{t}: Add {u}{b}{r} to your mana pool.