With the advent of her mod, she goes from being Thompson's kouhai to one of the strongest force shielders available. Too bad G36c mod exists now, but let's not talk about her.

Through the power of milk, when she lowers her force shield, she gains a decent evasion buff to turn her into a mixed force shield and evasion tank. While the buff requires there to be multiple enemy packs, any amount of evasion to go along with the force shield is welcomed. Oh, did I mention she also buffs rifles with her tiles now? That's a thing. The buffs she does provide aren't particularly useful for rifles, but it may come in handy.

She DOES require her unique equipment from the night map to function effectively, for the milk tin is all powerful. The mod equipment, however, is pretty garbage.

Her previous iteration can be found here

Babushka says not one step backward. Every seventh shot, she gives a damage bonus! Also, the thing starts active, making her one of very few buffers with a start-of-battle skill activation. Her first skill is still defensive in nature, and the percentages got bigger. She's actually useful in a number of situations, either for reducing enemy firepower in specific fights (usually Gundam or tank related) or just the straight DPS boost from the get-go. You only really need her up to Mod 2, but the Mod 3 art is cute.

Her pre mod form is here

So if it hasn't been said enough, absolutely get the Mod1 the very second you can. It's 200 fragments and some cores for a fair boost in performance. Extra stats, a bit more FP buff on her tiles, a little extra HP, and an improvement to the slowdown effect on the smoke.

The real problem is her 2nd skill is janky and not extremely practical. It's a little bit of a bonus, but not likely to make or break a fight. So yeah, the Mod2 isn't great. The mod 3 however, gives her a unique equipment that goes in the suppressor slot and is basically a suppressor with better stats (+5 EVA over normal) which helps her tanking ability somewhat. Whether this is worth it up to you, but definitely get the Mod1 at least.

The rest of this is basically the same song and dance where she has top class offensive buffs that continue to remain unmatched among SMGs, so you WILL likely continue to use her.

After literally years, M4 demonstrates WHY SHE IS THE HEROINE and becomes METAL GEAR.

She keeps all her old benefits but has 5 star multipliers and better stats now. This gets even better when Mod3 when she gets a unique that ups her firepower and ALSO gives her armour, so she can kinda tank in a pinch. Her buff tiles are ALSO slightly improved. Her mod 2 skill also tags enemies and enhances the mod skills of other Anti-Rain units.

The big thing however is the desperation mode. At mod2 onward, when 3 or fewer allied dolls are in battle (you can retreat 2 units to force this, or simply deploy her with a partial strength echelon), she pulls out the portable cannon and proceeds to deal hilarious damage that makes grenadiers wet their pants, as huge AoE blasts firing from every dummy. The blasts are kinda 100% accurate (the main hit can never miss, even at night, but the splash damage can. Its weird), and can partly crit (its complicated), and is meant to be a last ditch thing to save a fight under dire circumstances (of course, we instead abuse it). This is however, a doubled edged sword, as her RoF also goes down, so its possible for some enemies to slip by if you havent taken this into account.

Basically, Mod her first. She's pretty much priority #1 for modding.