As in the title, I am looking for any official description about Realm of Chaos for Warhammer Fantasy Roleplay(any edition).Preferably,something more specific than "the dark and chaotic place where demons live". (working on the campaign set in the domain of Nurgle.)
There is some information about the Realms of Chaos on the WHFRP wiki, including a map of the place. However, for an accurate description of the place, you gotta check the Warhammer Armies: Daemons of Chaos (8th edition), which includes descriptions of several locations inside the domains of Nurgle.
Here is a small excerpt from the book:
There is also information about the Chaos Wastes (which borders the Realms of Chaos) in the 2e Tome of Corruption, describing several locations and how followers of each chaos god should worship them. Certain places are directly influenced by their proximity to the Realms of Chaos, so you could use some descriptions from that book in your game. Descriptions here are far more detailed than those in Daemons of Chaos as well.