Helvault Ruins

{t}: Add {c} to your mana pool
{t}, Exile a creature card from your graveyard: Choose one of the exiled creature's colors. Add one mana of that color to your mana pool
When Helvault ruins is put into the graveyard from the battlefield, you may pay {4}. If you do, return all cards exiled with it onto the battlefield tapped under your control