The enhanced crystal key is an upgraded version of the regular crystal key that is used to open the Elven Crystal Chest in the upper level of the Tower of Voices in Prifddinas.
Players can create an enhanced crystal key via a singing bowl by combining a crystal key and 10 crystal shards. Doing so requires level 80 Smithing and Crafting to sing the crystal (the levels can be boosted), and grants 500 experience in both skills. If the player does not meet the Smithing and Crafting requirements, they can have Conwenna or Reese sing the crystal for them for an extra 5 crystal shards, for a total of 15.
The rewards from the Elven Crystal Chest include one uncut dragonstone and various other items that are generally worth more than the rewards from the regular crystal chest in Taverley.
The average drop value of the Elven Crystal Chest is 53,150. The profit from opening the chest is expected to be 31,142.03 after subtracting the cost of a crystal key (22,008).