Mana Vault doesn't untap during your untap step. At the beginning of your upkeep, you may pay . If you do, untap Mana Vault. At the beginning of your draw step, if Mana Vault is tapped, it deals 1 damage to you. : Add to your mana pool.
017 MPS_KLD ★ ENKirsten Zirngibl
™ & © 1993—2016 Wizards of the Coast
Notes: TODO: Update Copyright
Legal in: Freeform,Prismatic,Commander
Oracle Text (click to copy):
View this MTG card on Gatherer