I finally got the theologians guild as Milan, but with some oddities:
I got it at turn 97/98 and the next turn was immediately offered the masters version and the following another normal one.
Funny thing is, I used to pump out a lot of priests before and build all the catherdrals and huge versions, but only when I kind of stopped doing that and was focussing and killing the final enemy in my campaign (England) I suddenly got that offer.
Now I wonder, is it possible that you only get this guild after a certain amount of turns played maybe?
Bookmarks