Robbers' Den

As Robbers' Den enters the battlefield, you may reveal
an outlaw card from your hand. Robbers' Den enters
the battlefield tapped unless you revealed an outlaw card
this way or you control an outlaw. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks
are outlaws.)
{t}: Add {c} to your mana pool.
{t}: Add one mana of any color. Spend this mana only
to cast outlaw spells or activate abilities of an outlaw.