Oath of Kaya 
Legendary Enchantment
When Oath of Kaya enters, it deals 3 damage to any target and you gain 3 life. Whenever an opponent attacks a planeswalker you control with one or more creatures, Oath of Kaya deals 2 damage to that player and you gain 2 life.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL