Alchemist

The Alchemist combines two of the same thing into one better one. Open it with /alchemist, or from the Enchanter.

What it combines

2 enchant books of the same enchant (any levels) become 1 book with their levels added together.
2 Magic Dust of the same rarity become 1 Magic Dust of a higher rarity.

Put the two items in, check the preview, then click to exchange. Each exchange costs XP - between 800 and 10,000 XP depending on what you combine.