First of all that boss' become a kick-ass one. My high-end PC couldn't run the game without lag spikes. I've got stucked next to the wall by these red flaming walls, so I had to quit killing Vanaduke, because my party left after 20 minutes of killing Vanaduke, so nobody could help me get out of there.
I've made a picture, don't worry it doesn't show any of the new content.

http://i51.tinypic.com/dviuzm.png

I've just got to T3 right before the test content. I'm a noob at T3 at the moment. The dungeon seemed impossible to finish without any deaths. Those new arenas with respawning towers are definiately hard to do for even the hardcore/veteren gamers of SK.