Using magical essence on an item will make the items quality legendary. Legendary items gives an on equip increase of between 3 and 5 to a random skill. Using magical essence on an item that is already legendary will replace the existing skill bonus with a new one. When an item is transmogrified its durability counter is reset to its maximum. Transmogrifying does not change other aspects of an item, such as its max durability or weight.
The item must be dropped on the ground in front of the player before it can be transmogrified.