Oath of Teferi is a rare Legendary Enchantment card from Commander Masters (CMM), collector number 934. Current market price: $17.55, TCGplayer market prices via Scryfall.
When Oath of Teferi enters, exile another target permanent you control. Return it to the battlefield under its owner's control at the beginning of the next end step. You may activate the loyalty abilities of planeswalkers you control twice each turn rather than only once.