Dimitri, Power of The Source

Eminence —Whenever an Aetherborn deal
damage to a player, Exle the top card of that
player's library, if Dimitri, Power of The Source
is in the command zone or on the battlefield.
Flying, Menace
{u}{b}: Until end of turn, you may cast
spells from among cards exiled with Dimitri,
and you may spend mana as though it were
mana of any color to cast those spells.