Extradimensional Space

Extradimensional spaces within the Enerithan setting exist in a vacuum where the Astral Sea borders on the Far Realm. Any Bag of Holding, Heward’s Handy Haversack, Portable Hole, Compressed Cargo (see Cargo rules) or similar item that would open a gate to the Astral Plane instead opens a gate to the Far Realm.
When a gate to the Far Realm closes, unspeakable horrors may slip through. The DM is encouraged to be creative.