The Great Forge

The Great Forge enters tapped unless you control
an Obsidian Equipment.
{t}: Add {r}
{t}{r}{r}{r}: Roll a D20: Activate only as a sorcery.
4-10: Choose an Equipment card from your graveyard and put it into your hand.
11-17: Do the same, but put it onto the battlefield.
18-20: Do the same, but attach it to a creature you control.