Transmutation
Transmutation is only tied to transmuting Gemstones which is a type of item that is used to upgrade your Wearable items.
Transmuting a Gemstone will cost you your lower rarity Gemstone, X amount of Gold Bars and some special type of item that it not obtainable very easily. Chances of gaining this special item are improved by clearing higher Rarity Dungeons, opening higher Rarity Lootboxes and by increasing Luck attribute on your characters.