The Xaositects were one of the former 15 official factions in Sigil. The Xaositects (sometimes referred to as Chaosmen) are devoted to absolute chaos over all. They delight in acting contrary, random, and deranged. (Unless, of course, you expect them to do that, in which case they do the opposite.) Following the Faction War, the Xaositects (and every other faction) were banished from Sigil by the Lady of Pain.