Spider Cultist Cowl is a light armor set. The 5-piece set bonus adds 450 Spell Damage to your Destruction Staff abilities.
The Spider Cultist Cowl set is part of the base game. It drops in Fungal Grotto I and Fungal Grotto II in Stonefalls. Each set item is bound on pickup. You can acquire light armor, weapons and jewelry of this set in the Daedric motif style.