Loyalty

Loyalty is a characteristic that only planeswalkers have. Each planeswalker card has a loyalty number printed in its lower right corner. This indicates its loyalty while it's not in play, and it also indicates that the planeswalker comes into play with that many loyalty counters on it. See rule 209, "Loyalty." Damage dealt to a planeswalker causes that many loyalty counters to be removed from it. A planeswalker with loyalty 0 is put into its owner's graveyard. This is a state-based effect; see rule 420.