The Turnstone is a spherical object of great untold power appearing in IDW continuity. It is held and owned by Cherubae, a Dimension Z witch.
At one point in the past, Null and her cousin Noi Tai Dar, both demonic despots of Dimension Z, sought the Turnstone for nefarious purposes. They tracked Cherubae to Hirobyl and had her cornered, almost succeeding in their goal, before Cherubae's ally, the Trans-dimensional Cowlick known as Cudley, arrived to save her and the Turnstone from their machinations. Opening Moves #2