The normal Aberration boss is REALLY easy to Pass, but only if you know what to do. If you don't know what to do, here's a guide:

Requirements:

• 2 Peoples with Sniper pack (better to do so with your friend)
• Fast click skills (6 - 8 CPS is enough.)
• If you want to add a run to a leaderboard, must record everything and no timer needed. (There's an In-Game Timer.)

Start:

First of all, Aberration has a shield (The blue ball around him) When she does, DO NOT SHOOT! Once you entered Aberration, go to Ammo bag ASAP (As Soon As Possible), and wait until she will send "Corrupted Zombies" (If he don't do it as a first attack, rematch.) Once she sends you a 1 "Corrupted Zombie", take the SVD and shoot on him at any place. Then, Aberration were about to attack you. Dodge him. Then, if everything done right, go to Ammo bag, take the SVD and shoot on her head as fast as possible. Then, if there's only really small percent of health, good. Wait for her to become angry and then you needed luck, again. I mean, if she decides to show up some columns, good. Just avoid them. Then, when she tries to caught you, dodge her. Then, take the SVD and shoot on him. Once everything done right, you can get a good run. This may take some attempts and practice, as well. That's seems to be all from me!

P.S: Sorry if there's any grammar issues because I'm not English at all.