Clay

A Burst 2 support Submachine Gun who offers a DEF-ignoring damage buff and debuff immunity.
Unless many allies benefit greatly from DEF-ignoring damage, she feels weak compared with others in the same slot, so she is rarely a core pick.
Her value shows when paired with allies built around DEF-ignoring damage like Laplace, or when using immunity to hold out in fights that apply debuffs.

Stacking hits with normal attacks during Full Burst applies Victory Shout, briefly giving all allies DEF-ignoring damage and additional damage against enemy projectiles. Each time Burst stage 1 is entered, all allies gain debuff immunity once, and only if she has Victory Shout at that moment does Increased ATK based on caster's ATK extend to all allies. Using her Burst Skill briefly grants all allies increased DEF-ignoring damage, and her own normal attacks turn into DEF-ignoring damage during that time.

When Full Burst opens, keep firing normal attacks with the Submachine Gun without interruption to reach 60 hits. If the distance grows, fewer shots land and Victory Shout is delayed or drops off.
Keep Auto as the default. Turn on manual aiming only when hitting boss parts directly.

Prioritize Reload and Max Ammo to reach 60 hits with sustained fire. If the cube level gap is large, use the higher-level Harmony Cube over the theoretical ranking.

Set Elemental Advantage damage and ATK as a baseline. Not as much as a Shotgun, but add more Hit Rate and Max Ammo depending on range.

Increased ATK only works while Victory Shout is active, so raise Skill 1 first, then move on to Skill 2. Allies' DEF-ignoring damage is also on her Burst, so you can raise Burst later.

Used as a slot that counters with immunity in boss fights that apply debuffs, such as Special Interception, and the buff payoff shows when paired with allies that rely heavily on DEF-ignoring damage. She is rarely used as a core pick in general Story or Arena.

Victory Shout, stacked during Full Burst, raises DEF-ignoring damage for all allies, and her Burst Skill applies it to allies once more.
On entering Burst stage 1 she grants debuff immunity once, letting her counter enemies that apply debuffs.

Victory Shout only stacks during Full Burst and is short-lived, so she has to rebuild her hit count every Full Burst.
If few allies rely heavily on DEF-ignoring damage, spending the Burst 2 slot on her is not very rewarding.

She is included in the standard recruit pool.