Farming specific aetherials and aether corruptionsĪll of the rare crafting materials such as Tainted Brain Matter, Blood Of Ch'thon, and Ancient Hearts (very) occasionally drop from heroic chests, end boss chests, and one shot chests.There are three main ways to acquire Tainted Brain Matter, which we'll cover in depth below: Tainted Brain Matter is one rare material that players have trouble finding, especially as they level up and outpace the starting normal mode difficulty.