Limbo was the in between world that was the base of the Resistance. The plane is clearly identifiable by the fact that colour cannot be perceived while in within it and a person’s smell and taste is also diminished. Limbo is only accessible by portals, and these portals are generally created by magical objects such as lockets. These are held only by those who work with or head the resistance. Passing through the portals in and out of Limbo usually feels like passing through a film of water.
Due to the fact that Limbo is a plane between worlds, passing through Limbo and back into Eriallon can cause time jumps. For less experienced travellers these can deposit the traveller anywhere up to a week back and forward from the “true” date. For more experienced travellers, the portals through Limbo can be manipulated as to deposit them at a certain place in a certain time and is a powerful tool.
However, former leader of the Resistance and former party member Clemency betrayed the Resistance to The Advisor. This included giving him access to Limbo, and subsequently the plane was destroyed – it is unknown if Limbo is even accessible anymore, and if it is with The Advisor aware of it’s existence it is unlikely to ever be a stronghold again.