Card Text: Tap to gain an additional turn after the current one. Time Vault doesn't untap normally during untap phase; to untap it, you must skip a turn. Time Vault begins tapped.
Oracle Text: 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. Tap: Take an extra turn after this one.