Hmm, I just turned level 28 and was level 27 at the time. I believe the opponents were somewhere around level 23 - 25. I didn't get any damage, however, I just kept seeing all these zeroes come up for my damage. Oh, I also killed Zagan extremely easily as well, I can't remember what level he was.
I am just finishing up most of the side quests before I tackle the flying fortresses. I entered Stone's at about level 24 and ended up having my ass handed to me most of the time, but managed to defeat Zanlosch just the same before I got the hell out.