Mad Alchemist Trophy trophy_alchemy_lab

What it is for

Loot: exists to be sold or used in a recipe.

Sells to an NPC for about 53,620 gold. Weighs 20 of your carry capacity — and weight is what stops drops once the bag fills up.

The best source is Mad Alchemist, at 8.0% per kill. You can farm it at Forgotten Lab.