MAGIC: THE GATHERING
Time Vault enters the battlefield tapped.
Time Vault doesn't untap during your untap step.
If you would begin your turn while Time Vault is tapped, you may skip that turn instead. If you do, untap Time Vault.
: Take an extra turn after this one.
While Time Vault looks fairly innocent on the surface, this two-mana artifact can turn into infinite turns very quickly with cards like Voltaic Key or Tezzeret the Seeker. There's a reason why Time Vault is banned in every format except Vintage, where it falls onto the Restricted list alongside the Power 9.