Primordial Goo

Wondrous item, rare

This sticky, translucent ichor contains otherworldly magical properties that can change the material nature of objects. When you bathe a weapon in this goo for 8 hours, you can change the damage type of the weapon permanently. During this bathing ritual, you must deal any amount of the desired damage type to the goo so it may replicate the damage. Once you have undergone this process, the goo becomes inert and cannot be used again.