Erasure, the Fiend Caster

{2}, Sacrifice two creatures: Create a 1/1 black
Imp Nightmare creature token with "Whenever
this creature dies, each player manifests the top
card of their library."
Whenever a face-down creature dies, its
controller reveals it and exiles it face-up. For
as long as Erasure is on the battlefield, you may
cast cards exiled this way and may spend mana
as though it were mana of any color to
cast them.