Mending Mixture

Don't try to drink it. You will not like the consequences, trust me.

It can be created in a Crafting Table, via shapeless recipe:

Alternatively, there is a small chance to find it in chests generated within End City.

Allows you to fully restore durability of basically any damageable item, by combining the mixture with it in a crafting grid:

Leaves behind empty Glass Bottle after being crafted with item.

Any enchantments, effect and data of the original item is preserved when repairing. Therefore, Mending Mixture is a perfect way to repair expensive tools and armor with lots of enchantmens on them, while regular Anvil will consume a lot of resources and experience to do that.