Steelsap

Steelsap is a material used by various artisans in the Dungeon to create highly durable items. It is said to come from an enormous tree up above ground. It is used in the Forge as a kind of metal, where it is heated in a cauldron in order to make it more workable. As noted by the Smithsbat, it has fantastic material properties but is difficult to work with. It was used by the Adventurer, along with some iron, to create the Steelsap Alloy Axe. It is a pale blue in color, and has a pearlescent sheen to it.

First appearance: https://twitter.com/Tuckiozi/status/1238180148706492416