Stygian steel

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Stygian steel is a special form of soulsteel made from souls and death ore mined from the Veinous Stair. It far superior to soulsteel, as it is extremely durable, strong and tough, as well as capable of causing aggravated damage to wraiths. Stygian steel is extremely difficult to manufacture as it must be tempered by Oblivion itself, and is expensive when it can be acquired; most weapons made from it are therefore held by high-ranking members of the Hierarchy.

• WTO: Wraith: The Oblivion Second Edition, p. 234