Maxwell: Ordinary Mechanic

A Burst 2 Supporter used when building a max-HP-scaling DPS squad in Solo Raid against Iron Code enemies (= Wind advantage).
Her ally Increased ATK comes from Maxwell's own final max HP, so it only becomes strong alongside HP buffers like Rouge and max-HP-scaling DPS like Laplace: Ultimate Hero.
Outside that lineup, her buff amount is smaller than general Burst 2 units like Crown and Nayuta, so she's rarely a main pick.

Each Full Charge raises all allies' max HP by 1% based on the caster, up to 30 stacks, and also fills ally Burst Gauge. Using her Burst Skill grants all allies Increased ATK proportional to Maxwell's final max HP for 15 seconds and stacks one level of Overcurrent on herself. So the longer the battle, the more ally max HP and the resulting Increased ATK grow together, and max HP buffs like Rouge's raise the Increased ATK further.

During Burst, her weapon changes to Matis UberBusterB, a single-shot pierce sniper rifle, and higher Overcurrent levels reduce its charge time from 3 seconds down to 0.4 seconds. Her Burst also grants all allies increased attack damage for 10 seconds, and each time Burst stage 3 is entered, all allies gain increased attack damage for 5 more seconds.

Leave her on auto by default. She needs Full Charges to build max HP stacks and fill Burst Gauge, so don't use tap-firing that cuts charges short.
Even slotted as a totem that leaves bursting to other Nikkes, her Full Charge effects and Burst stage 3 entry buff still apply.

Her buff amount comes from her own final max HP, so use the Vigor Cube first. If your Vigor level is low, use the Resilience Cube to keep Full Charges going without interruption.

When used as a buffer, take Charge Speed and ammo first to increase her Full Charge count.

Her ally Increased ATK and the effect that fills Burst Gauge are on S2, so raise it first. S1's max HP stacks raise the base value for S2's Increased ATK, so raise it to 10 when she's in a main Wind Raid squad. Burst at 7 is enough.

Used in max-HP-scaling squads for Solo Raid boss fights against Iron Code enemies (= Wind advantage). In Story and Tower, there's little reason to replace your existing Burst 2.

Her ally Increased ATK is based on final max HP, so it grows as she receives max HP buffs during battle.
She fills ally Burst Gauge with every Full Charge.
She places little burden on Overload and skill level investment.

In squads without max-HP-scaling DPS and HP buffers, her buff amount is small.
It takes time to reach 30 max HP stacks, so her early-battle buff is weak.