Mana Vault

Mana Vault doesn't untap during your untap
phase.
At the beginning of your upkeep, you may pay {4}. If you do, untap Mana Vault.
At the beginning of your draw step, if Mana
Vault is tapped, it deals 1 damage to you.
{t}: Add {c}{c}{c}. Play these additions as
interrupts.