Skin Button

The new skins button

Skins is a feature, introduced with the Celestial Patch (24th Nov, 2017), which lets you alter the appearance of a selected range of heroes while granting them bonuses while wearing the skin.
They can be acquired as Universal skin shards-icon Universal skin shards from defeating bosses on Celestial Island once your Watch Tower is at least level 11 and you may encounter rare, rainbow aura islands, which grant 1 shard as well. The loot is 1 shard at a time, and a total of 10 fragments are required to craft a skin. They can be part of Value Packages and Events as top-tier rewards.