He is a really nice guy. He means well, even if he can’t always make the rarest items. Alchemy is hard.
The Alchemist is a friendly NPC who resides in the Nexus. He is next to the Mystery Box and above him is the Daily Quest portal which leads to The Tinkerer. You can use the Tokens which you get from completing quests from The Tinkerer or spend realm gold to get various items such as rings, skins, keys, weapons, and cloths. When you use a token, 3 items will be chosen randomly and will swirl around the main blue orb. You will then have 10 seconds to choose from 1 of the 3 orbs to receive an item, further, you can pay an extra fee for another chance at 1 of the remaining 2 items, although the choice of orb does not affect the outcome, as it is random.
Currently, The Alchemist does not have a set schedule of when he will appear and disappear.