I'm trying one of the missions solo.
I'm a tank/mage (warrior/elementalist) and I have a monk henchman (healer). LOL, the battles are definately different than what I've experienced before. The toughest battles so far have been a stalemate. The mob takes at most 1/4 health from me and the monk just heals, but my regular attacks also only hurt the mob at most 1/4 health, before he heals himself. I can go eat for an hour and come back to see nothing changed. The key (and I suppose this is where "tactics" come in) is to use a combo of moves (AoE, Staggering blow, Mighty blow, Counter blow, inferno) in the right order to finally kill the mob. IMO some mobs are regenerating/healing HP way too fast, including myself.