Realm

A Realm, or Universe is a massive plane of existence that lingers within the greater multiverse. Realms are separated remain separated by spatial matter, held together by vast quantities of natural energy. Different realms can also be located closer or further away, and thus can be either harder or easier to gain access to. No one quite knows how many universes currently exist in the Tales of the Forgotten series.

Pocket Dimensions
All realms have their own set of pocket dimensions that can be reached only while with in that particular universe. These dimensions have a range of uses, though the primary applications are to store items, or to serve as imprisonments for either dangerous relics, or entities.

Traversing Universes
As a result, to break free, one requires an enormous amount of energy to be concentrated in a particular space in order to rip open a portal that will allow one to transverse into a different area.