Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

What happens if I take for example a Chaos Renegades Demagogue with X devotion? It states if you take a devotion he must be the armies warlord.

Except... He can't be. He's in an allied detachment. There are other forgeworld characters that have the "must be your armies warlord" rule also.

Does the table catch on fire? Whats the correct ruling here?

If he must be warlord, he can't be in an allied detachment.

You can't make him your warlord so you can't give him a devotion

Allied Detachment + Must be Warlord = An illegal army

Indeed, not sure why "break no rule" isn't the obvious answer here.