So there currently exist multiple STEAM groups that cover this mod.

NEW STEAM GROUP:
Beginning of the End Times [Owned & Created by The Dev team].
https://steamcommunity.com/groups/CoW-BotET

This new group has been created to coincide with this new forum and to better assist with communication and organisation of our growing player base. (and eventually the latest patch)
We appreciate all the effort and involvement the community has put into the previous groups, and you are free to continue using them as you wish.
The Dev team intends to use this new STEAM Group as our primary STEAM group for announcements and organised events going forward.

Please pass on this new group to your fellow players, and we look forward to seeing you all there in the coming weeks.

The other groups are:

Call of Warhammer 1.6 Multiplayer (Originally created for Rage of the Dark Gods). [Owned & Created by popular YouTuber IndyPride (milkandcookiesTW)]
https://steamcommunity.com/groups/callofwarhammer

CoW end times [Owned & Created by community member MysticFade]
https://steamcommunity.com/groups/TWCoW

End Times Hotseat [Owned & Created by community member Stevothree]
https://steamcommunity.com/groups/EndTHS