The Quest for the Lost Eternia Shards Part 3 Add-on for Dungeon Defenders has 4 achievements.
You retrieved the Yellow Lost Eternia Shard from the cold waters of Aquanos!
You solved the 'Riddle of the Deep' Challenge!
You retrieved the Yellow Lost Eternia Shard from the cold waters of Aquanos... on Nightmare!
You solved the 'Riddle of the Deep' Challenge... on Nightmare!