What counts as “spell and ability damage?” What does this card do?

“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.

Related: Rule 417.6.a, Rule 417.6.b, Unyielding Spirit