With LTLX7000 being out, the main question asked of most shotguns is "are they as good as LTLX?" As for M26-MASS, she does her damn best trying to be. While LTLX has her SUPER dumb damage mitigation in her active skill, M26 has it baked in as a passive. If any damage she takes is 5 or lower, it’s completely ignored, as if she had very good flash rounds. This is applied AFTER armor mitigation AND flash rounds. With flash rounds, she’s essentially immune to anything 8 damage or lower, which is very strong. However, if the enemy does too much damage, this passive does nothing. However, in current day, LS26 exists. This fixes damage taken to 5 which, spoiler, is negated by MASS's skill. Can be very strong to force MASS to tank some insane things. How often will that be used? Eh. It's neat at least.

The one thing she does have going for her with her passive is that she can actually mitigate damage that bypasses armor. You can entirely mitigate stuff like grenades through it. You could sit in gundam range for a bit and not fussed about it. You could even sit in Typhon lasers and be fine. (Depending on firepower of Typhon, please do not attempt without consulting a local doctor)

Overall, she does fall short of LTLX just due to the sheer power of doubling your armor along with 20% DR. The utility of her active also is less relevant compared to LTLX. Removing HP shields and buffs (which get far more common) is stronger than a Molotov and DR to backline. To add to that, the 6 second initial cooldown hampers the effectiveness of the backline portion of the skill. This is because most things that do target the backline would already be skullfucking you at that point. Other cases this is bad include maps M26 shouldn’t be brought to for one reason or another, like when shotguns are bad for it in general or you can’t use machine guns.

OBEY. Made from a less-lethal shotgun meant to give police forces more options to put down people without killing them. In G&K's case, however, she certainly helps with takedowns.

Incredibly good stats for a shotgun, good formation buffs, and her skill has the unique ability to cancel enemy buffs. These buffs include ENEMY SHIELDS (including Patroller shields) and stat buffs (including bullshit enemy evasion buffs). Her mechanics are unique, so she actually ignores normal knockback immunity. Oh, and her armor buff stacks are multiplicative. Unfortunately, the Minotaur's damage reduction is a weird thing that can't be removed, but regardless, you get so much utility from her. Even if you don't need her skill, her stats are just that good.

If you don't have her, get her from a True Core Mask or something. She's just too useful in things like later Theater events.