I know what i normally do (this happens alot in PUG's). In sewers i normally hold boss until all can run back to me for backup (not that hard on my dex bear lol). In a mob situation i normally keep up my spamming attacks and watch my health super close, this made me find out I can solo like any sewer level there is except maybe Cockroach who has a pretty hard hit, and Queen who heals too fast.

I had one team that kept calling my lvl 48 bird "ThelonearcherII" when the team died so much I soloed Overlord's level. (BTW the team was all 52, sad right?)