The Fem-Mech Boss is the first 3rd Level Fem-Mech Duke will encounter in the game. She is a lot more durable than the 3rd Level Fem-Mechs Duke will encounter later on at Morphix's space station and any 1st and 2nd level Mechs he had fought previously. She's seen in the third part of the seventh chapter "Deviant Drilling". She is the last line of defense stopping Duke Nukem from reaching Morphix's space station.
Duke Nukem about to fight the Fem-Mech Boss
Encounter
Duke will encounter her on top of Morphix's GLOPP Rig and after a brief talk the fight begins. Her Electric whip does 40 damage which means only a few hits can kill Duke. Like any other Fem-Mech, she likes to roll in Dukes direction and then slash him with her whip and her combat maneuvers are more-or-less the same, so if the player was good at dodging other Fem-Mechs' attacks, this battle won't be much of a problem to them.
It can be quite hard avoiding her attacks since she pushes Duke everytime she rolls on the ground; Duke needs to do a lot of jumping in this fight because she can easily push him off the edge and sometimes strike him when he's in mid-air with her whip, so timing is important. Duke needs to be careful when using explosive weapons as she's a melee boss and there's a good chance he could get caught in the impact, therefore a lighter weapon like an assault rifle would probably work better. This is arguably one of the hardest boss battles in the entire game, but if the player is good at avoiding her attacks, they will have no trouble with her, however that will depend on how quick they are to react to her charging them.
When Duke defeats her, he remarks "Oh well looks like I've broken another woman's heart." and then proceeds to the nearby teleporter to be transported to Morphix's space station, thus beginning the final chapter - "Orbital Oblivion".