Portal

Portals are physical objects that can be found throughout many realms, and take on an appearance typical of that realm:

Falderal: magic mirrors, glowing magic pools, palantirs, runic stone/wood archways; These glow with a telltale blue-white moonlight.
Halcyon: various
Phantasmic Sea: doors
Lugubria: chimney
Ephemera

A portal allows its user(s) to travel instantly from one point in a realm, to that of another portal, in the same or a different realm. Portals and their connections occur naturally and randomly, and vary from stable to volatile.