From the Mask Makers of Dereth quest introduced in Tricks and Treats.

Mosswart Head
Value: 0
200 Burden Units
A festering, foul-smelling decapitated mosswart head.

Notes

You give Janda's Apprentice Mosswart Head.
Janda's Apprentice tells you, "Well here goes nothing. Okay paring knife to make the eyes... whoops! No problem, no problem. Yeah that works. Whew!"
Janda's Apprentice gives you Mosswart Mask.