Onakke Oathkeeper is a rare Creature — Ogre Spirit card from Commander Masters (CMM), collector number 722. Current market price: $10.17, TCGplayer market prices via Scryfall.
Creatures can't attack planeswalkers you control unless their controller pays {1} for each creature they control that's attacking a planeswalker you control. {4}{W}{W}, Exile this card from your graveyard: Return target planeswalker card from your graveyard to the battlefield.