I'll go ahead and say that a level of 97+ with a Might of 500k+ is HIGHLY
recommended. 450k+ is enough to survive, but not enough to actually be a factor. Ideally, lets say you're in a party of 3. If a fight takes longer than 5 turns, you're really, really dragging the run down as bear in mind that while your party is engaged in battle, mobs may be walking past you heading for the team gate...
The Mimics have a buttload of HP, 32k to be exact. These things FULL FORMATION
ice anyone on the 3rd turn, and occasionally you get 2 or maybe 3 of them in a fight, usually only 1 though. However the priority is to drop the Mimic ASAP, preferably on turn 1 if at all possible... Which will not be possible with only 450k+ Might so you'll probably be taking till turn 2 or 3. If it gets to turn 3 then SOMEONE is going to get full formation iced.
At least bring one merc with a decent hard hitting weapon (+6 or better).