Artifact

Mana Vault does not untap during your untap phase. If it remains tapped during your upkeep, Mana Vault deals 1 damage to you.
o4: Untap Mana Vault. Use this ability only during your upkeep.
oc
T: Add three colorless mana to your mana pool. Play these additions as interrupts.

Artist(s): Mark Tedin