Talk:Dungeon/@comment-217.136.241.235-20200109091749/@comment-38954537-20200111013854

They're like normal keys when fighting/raiding dungeons, except they can be used for any color, not like the 10 free keys we get daily, which can only be used for the same day's color. In addition, you can keep skeleton keys and spend them whenever you like, although they cost gems to buy, so they're only useful if you're in a "hurry" to finish a dungeon when you have a powerful deck like during an event for example.