while slaying, wearing a shiny four-leaf clover necklace i receive a message in the chatbox which reads "your shiny four-leaf clover necklace shines briefly and you receive a medium prismatic lamp" followed by "your crystal amulet has produced a crystal motherlode shard" i'm assuming it is referring to the crystal amulet that was stored in my bank when examined the "crystal motherlode shard" (which seems to be stackable) reads "the elves would be very interested in these shards. You'll be able to claim a reward when the city opens."
