When I convinced the magus who is with the collective to leave the collectives side, I got an error saying I was missing a sound file called Angry Avenger. I copied the same file from another previous version of the game and that solved the issue, but the most recent version of the game might not have it.
And after the fight that came after that, not sure if intentional but I can't talk to the magus, he just stands there and I'm really wondering if that it's a bug.