Lumicite Shard
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The Lumicite Shard is a Key Item in Chrono Trigger. It can be obtained by defeating or Charming the monster Wonder Rock, which can be found at Lost Sanctum on rare occasions and/or the Dimensional Vortex. It can be given o a shopkeeper found in Reptite Village (in the Lost Sanctum to make the armor Elemental Aegis, a powerful piece of armor that increases defense by 92 points (second only to the Prismatic Dress) and makes the wearer immune to all elemental attacks. The downside is it can only be equipped by Lucca.