Twilight's Mist

Whenever a black spell with 3 or more colors in
its mana cost is cast, you may return Twilight's
Mist from your graveyard to the battlefield.
{b}{b}, Sacrifice Twilight's Mist: Regenerate target
white or green permanent. If it regenerates this
way, gain control of it and it has "{b}{b}{b}, Exile
this permanent, then return it to its owner's hand
at end of turn: If target artifact or enchantment
would enter the battlefield this turn, exile it
instead."