https://www.youtube.com/watch?v=9Ku49GHHKGE&feature=youtu.be be sure to like and share this FAST before it is patched!!! Splicer Keys are used for 3 things we currently know of(please correct me if wrong). You need one to start the Gjallarhorn quest while on patrol in Plaguelands To get back into the Archon Forge Arena when you die, you will use a key to get back in There are secret locations on patrol Plaguelands that you can go to and use this key to open chests(after killing enemies in the area). EDIT: You can hold 10 keys per character and 10 in your vault, for a total of 40!!!