You can change the look of an epic or legendary item for 10 mushrooms in the blacksmith's customization section. Items whose appearance can be changed are highlighted in the backpack or when equipped.

Click on an equipped epic item or an epic item from your backpack whose look you want to change. It will be moved to the respective area at the blacksmith automatically. Alternatively, you can also drag it to that area.

Now click on the adjacent button to select an epic item, which must be in your scrapbook, from which the appearance is to be transferred to the first selected item.