| Spoiler warning!|
This article contains major plot details or explains info that the player may want to find out on their own.
Before the fight, Jennifer offers an alliance to Albert. Accepting this offer will avoid the battle and plays one of two endings, but is not sufficient for the "Shortest Purification Time" leaderboards. Declining the offer will begin the battle, and winning will put your time on the aforementioned leaderboards.
Jennifer follows closely behind Albert while attacking him. She often sways to the sides in a slight arc, which can make it difficult to aim. Unlike Murray's fight, Jennifer's fight is not cut into phases. She will begin with a shield that must be destroyed in order to actually harm her and this shield will periodically be restored. In addition to the shield, 20 machines around the room will heal Jennifer if she is near it.
This battle can easily drag out for a long time due to the need to destroy at least some of the machines. Various survival and exploration items can be helpful, including decontamination pills, nanocasting kits, bandages, marsmari, and spare weapons; the normal essentials, like medical kits, shouldn't be forgotten.
The room hovers over a pit of lava (which is mostly aesthetic since you can't fall) and is mostly composed of walkways. Jennifer hovers, so she is not restricted to the walkways. The very north, east, and south ends of the room have small power recharging stations available with individual capacities. Due to their low capacities, you should try recharging whenever you pass by one if you can spare a moment. If you can manage this even half of the time, you shouldn't have many problems with power.
There are 20 machines strewn about the room that can be destroyed. Since they heal Jennifer, destroying them is necessary to killing her, and they should be your initial priority. There are 4 machines in each corner of the room, 2 of which must be shot (by something that's not a shotgun), in addition to 4 more machines that surround the center platform and also must be shot. Each machine has high HP, and will explode violently when destroyed. This explosion can easily be fatal, so the last few hits should be dealt with a gun, or an escape plan should be prepared.
Since Jennifer needs to be near a machine to be healed, it may not be necessary to destroy all of them if you can fight her in a smaller area that has no functioning machines. However, the restricted space may make the fight more difficult.
During the fight, Jennifer will summon normal mutants, muscled mutants, and big fat mutants constantly. While big fat mutants may be easy to avoid due to their speed, the other two may need to be dealt with if you want more time between waves of big fats. If left alone, the big fats can accumulate quickly, especially because her preference to summoning them over the other mutants seems to increase as time passes. The summoning of a mutant is prefaced by a large orange light centered on the spawn spot; the light itself is harmless.
When Albert is far from Jennifer, she will fire a slow projectile about once a second. They deal a small amount of damage and slow Albert. However, they can make approaching Jennifer, and crossing the walkways that end up at her, difficult.
When Albert is closer, a little beyond SMG range, Jennifer may use two bullet-based attacks. One fires three waves of tiny, randomly-dispersed projectiles, similar to the Pre-Martian's but with a wider angle. It is prefaced by a similar animation as the Pre-Martian's, as well. The other attack is a rapid-fire projectile attack that is more focused on Albert. This attack is prefaced by Jennifer putting both hands together and pulling them to one side, similar to the Pre-Martian's blue ball attack.
Occasionally, Jennifer will place three bombs near Albert that explode after about a second. Like most explosions, these can be deadly, if not fatal, so recognizing when this occurs can be crucial.