I doubt your issue is DPS and is more likely strategy related.
Pre-move toons to where blob spawns, start mission, have a hot key for them to start attacking while you run to the blob and autoinv the item given at the beginning.
When blob dies, do same thing with Spider; meaning attack before it becomes "live" go through it's bs warping to buildings, always kill the widow add before the spider.
Have a hotkey to target lich and run group to and attack it for constant smashing, also, I would burn at this point to avoid getting a mummy.
When Shalowain spawns, stay away from her with all toons until AFTER she emotes (about 10-11 seconds depending on your lag)
Once she emotes, run to a corner of the immediate area, she arrives, beat on her until you see the auras getting close, then run to next corner +1, rinse repeat until she's dead