The Impact Sigil has been added to Enchantment, and the Shell Sigil has
been added to Conjuration. These sigils will prevent the explosion of a
mushroom or spore sigil from harming an item they are attached to.
However, they may not be attached to an item that already has a flame or
holdfast sigil attached, nor can flame or holdfast sigils be attached to
items with impact or shell sigils.

Penned by my hand on the 18th of Severin, in the year 302 MA.