Rona, Disciple of Gix

When Rona, Disciple of Gix enters the battlefield, you may exile target historic card from your graveyard. (Artifacts, legendaries, and Sagas are historic.)
You may cast spells from among cards exiled with Rona.
{4}, {T}: Exile the top card of your library.

Mirran Spy

Flying
Whenever you cast an artifact spell, you may untap target creature.

Priest of Yawgmoth

{T}, Sacrifice an artifact: Add an amount of {B} equal to the sacrificed artifact's mana value.