Probably a bug, or may be they managed to finish the ritual
I hadn't thought of that scenario, but it would explain why the druids suddenly attacked the tieflings and us. I could not choose sides. It was druids against everyone else.
But, that means one has to be realy quick then to avoid it.
I will continue this game for a while, as I'm still looking for the corpse of Khaga. (It was Gale that gave her the final spark, actually)
Then I may go back to a save before all this and try to pay more attention.
Among the corpses there was the guy that you save from the underground tunnel, and he got a crown to open the library door, I didn't need Nettie.
And from Rath's corpse I even got the wolf rune. So I got deeper down the cove than in any of my previous games..