Tomb of the Beguiler is really the only challenging dungeon from krok at least to me :P I had to group up with a few others to complete it. If you are having trouble with any of the dungeons, ask me and we can set up a time :)
i think the tomb of the beguiler is even for a lvl 33 cause i tried first boss 1800 health second i think 2800 health and the rest of tomb of the beguiler fire bosses 2000 health. last boss in the tower 3400 or 3800 health. is he like the first boss?
Tomb of the Beguiler, tried get past the first boss but couldn't, so I focused on Marleybone and other sidequests to gain a bit more health and tried again. Now I'm a lv 37 and i still cant get past him, even with all the shields and blades i obtained. But then again I've read about the Upper and Lower Zigzag.