Unyielding Spirit

“Spell and ability damage” on Unyielding Spirit is meant to encompass damage dealt by spells and abilities, but not damage dealt by other things as a result of spells or abilities. It will receive errata to clarify this.

Prevent all damage that would be dealt this turn by spells and abilities.

Q: So… What does this card do?

Most spells and abilities that deal damage just say “Deal 3” or similar. Unyielding Spirit stops damage from all such spells and abilities. Other cards, though, specify a source of the damage.

Damage dealt by spells is damage that a spell instructs you to deal without specifying that some other object deals it. Damage dealt by abilities is damage that an ability instructs you to deal without specifying that some other object deals it. (All damage dealt by abilities is also dealt by the object that's the source of the ability.) If a spell or ability instructs a particular object to deal damage, including the card the ability is on, then that object is dealing the damage, not the spell or ability. So Unyielding Spirit does stop damage from Void Seeker, Stormbringer, or Yasuo, Remorseless, but does not stop damage from Challenge, Last Breath, or Carnivorous Snapvine.