This Boss battle may seem hard, but it can actually be easy. Long before the 
battle, purchase all upgrades that allow you to do +3 Devastator attacks, upon 
max health. It is also recommended you get all upgrades possible through the 
"Consume" option. The Boss is massive. Notice that under her health bar are 
other bars. These are the Boss' stabilizers, making her vulnerable only after 
you have severed them. At the beginning of the battle she will do a scream 
attack. Be careful. Scale up a building or whatever else you can. It is very 
easy to avoid. You will also have Hunters and Infected chasing you. Use the full 
body armor and claws/blade. Max out your health by running around and consuming. 
It is easy, and the only issues you might have are Hunters, but with the 
upgrades one hunter can nearly boost your health to max, allowing for maximum 
Devastator attacks. This is one of the first Devastator attacks you learn. Scale 
a building, boost over to her, fall, and initiate the attack. You will quickly 
see the Boss' stabilizers are being damaged. Note: Every round the stabilizers' 
health will increase, meaning that you have to follow the tactics in the same 
way, and it will just take slightly longer. Strike her with the Devastator. You 
should have a chance for more, unless she does multiple attacks (green orbs that 
track you, spitting concrete, and screaming). The armor reduces the amount of 
damage inflicted, allowing you enough time in-between attacks to initiate the 
Devastator again. Once the stabilizers are destroyed, she will fall, and you can 
attack normally. She will then retreat (leaving you plenty of red health orbs to 
consume) before shooting out of the ground again, with more stabilizer health 
and "backup". Ignore the backup. This tactic works nicely, but if you get low on 
health, run away from her view, and keep consuming. After she falls a total of 
three times, you will have defeated her.