The ability to mentally control "stepping discs", which allowed them to teleport from one location to another, which are part of a dimension known as Limbo. This dimension is specifically known alternately as "Demonic Limbo", "Limbo-Belasco", or "Otherplace".
However, when they mentally call for a Stepping Disc they must use Limbo as a midway point before they can teleport to an alternate location. High-level users have succeeded in teleporting themselves across continents, from one continent to another, and even interplanetary and intergalactic distances on occasion. Apparently some can mentally scan Limbo while on Earth in order to locate whoever they wish to teleport from Limbo down to her on Earth. Unlike most other teleportation abilities, they ccan teleport through time as well as space. They have teleported moments, days or centuries into the past or future. Low-level users have difficulty modulating this ability and often inadvertently travel through time and space when intending to teleport only through space.