Nightmare Shepherd

Does this ability work on animated non-creatures (be it enchantments from Starfield of Nyx, or any other case)?
If I had an animated Saga that "dies" does it return as a 1/1 Enchantment creature indefinitely, or does it return as just the saga, if at all?

My understanding is it checks "as it last existed on the battlefield" but gatherer doesn't have any clarification on this one yet.