Eternity Engine

At the beginning of your upkeep, choose
creature, instant, or sorcery. Until the beginning
of your next upkeep, you may cast spells of the
chosen type from exile and you may spend mana
as though it were mana of any color to cast them.
Whenever you cast a spell from exile, exile the
top X cards of each players' library where X is
that spell's converted mana cost.
The things these people leave just laying around!