The demonic sigil mould is used to make demonic sigils, which are used in the Shadow of the Storm. Players may obtain a sigil mould from Jennifer, a disciple of Denath, who can be found in the demonic throne room under the Ruins of Uzer.
To make a Demonic sigil, players must have 30 crafting and use a silver bar on a furnace whilst having a sigil mould in their inventory. The sigil is used to summon the demon, Agrith-Naar, in order to defeat him.
The demonic sigil mould is kept after completing Shadow of the Storm, however it can no longer be used to make a sigil, with the response: "There is no need to make another sigil now you have defeated Agrith-Naar." If lost, it cannot be reobtained.