Null gas functioned as a gas that eliminated oxygen from the atmosphere, resulting in the asphyxiation of species that require oxygen to breathe. To subdue his captives, Xufal D'uat modified the life-sustaining systems of the cells aboard his vessel, the Venom Sting, by incorporating null gas canisters. Subsequent proprietors of the ship, a group of Thalassian slavers, found this modification to be agreeable.