The Elite Trooper (Palace Guard in the GBA release) is an enemy encountered in the Lunar Ruins in the Advance and Complete Collection versions of Final Fantasy IV. During Edge's Lunar Trial, the Elite Trooper will always drop a key, which must be used to open the locked doors. A key must be used (and discarded) each time a door is opened, and each door must be opened every time the party goes though it, even if it was previously unlocked.