Ash Zealot tends to make Zombie decks and Flashback spells sad. However, it’s not a complete Graveyard hoser like Grafdigger’s Cage is. Cage will stop creatures from coming back from the dead even if they’re reanimated some other way, like via a Unburial Rites, or Undying. Ash Zealot only cares if something gets cast from the graveyard. She won’t trigger from a Geralf’s Messenger coming back, or a big creature being resurrected via Unearth or a reanimator spell. So long as nothing was cast from a graveyard, she won’t trigger.