This item is autokeep. This means that if you die with it, you will always keep it.
Despite not being a typical magical item, silly jester boots gives a greater magic defence bonus but don't have a magic attack bonus, so mystic boots are still usually a good choice overall.
* The blue mystic boots can be bought from the Wizards' Guild in Yanille.
* The light mystic boots can be bought from other players or rarely dropped by Cockatrice and Basilisks which require 25 and 40 slayer to kill respectively.
* The dark mystic boots can be bought from other players or rarely dropped by Infernal Mages, which require 45 slayer to kill.