Mana Vault

Mana Vault doesn't untap during your untap
step. 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}.
Such volatile power is sealed away for a reason.