After defeating Rennala, Queen of the Full Moon in Elden Ring's Academy of Raya Lucaria, players will encounter a chest. Fans will not be able to open Rennala's chest straightaway, though, as they must first obtain the Discarded Palace Key. This guide will detail exactly where players can find that key, allowing them to unlock the Raya Lucaria Grand Library chest in Elden Ring and claim the reward that is inside.