To lose one's memories can be damaging to anypony pony especially to those that truly cherished those said memories. A disaster that caused Luna's memories to scatter along the wind, Celestia must retrieve her memories in order to return her sister back to normal. However, with powerful memories like Luna's, there will always be grave consequences to those whose heart wrought by evil intentions will do anything for the small power residing within the memories of Luna. Even those from far-away dimensions.