Great, I thank you so much!
I'm currently in the ruins now, at level 2 and I have Shadowheart, Lae'zel and Gale in the party and it's smooth, really smooth, so far.
I use this campaign now as my final preparation for my "tactician" playthrough, I tried tactician already but it was still a bit too hard for me, but next time I will know what to do.