Vesti

A Water Code Burst 3 Rocket Launcher DPS who chains Bursts to raise Survival Instinct2 stages, then aims for Missile Container and enemy-wide explosion damage.
She is rarely a main pick for Story, bosses, or Raid main slots, and her Burst cuts allies' Full Burst duration by 5 seconds, burdening team rotation.
Vesti: Tactical Upgrade is the better choice for the same role.

Each Full Charge hit increases her explosion range. Each Burst Skill use stacks Survival Instinct2, granting long-lasting ATK, Crit Damage, and Crit Rate in sequence. Her Burst Skill deploys a Missile Container that hits the lowest-HP enemy every 1 second, and enemy-wide extra damage grows with Survival Instinct2 stage. At the same moment, all allies' Full Burst duration is reduced by 5 seconds.

Keep the explosion range buff up with Full Charge, then fire continuously.
Use her Burst Skill multiple times to raise Survival Instinct2 stages, then use her enemy-wide Burst when the stage is high.
Leave her on auto by default, and only time Survival Instinct2 stacks and Burst by hand.

There is not enough evidence in the recent meta for pairing her in the same squad.

Align her Rocket Launcher Charge cycle with ammo recovery and reload. Adjutant Cube supports Charge Speed. If Harmony Cube levels differ greatly, use the higher-level cube over the ranking.

To make the most of Survival Instinct2 stacks and explosion range, prioritize Charge Speed and Max Ammo. Match Crit Rate and Crit Damage to Survival Instinct2 stages 2 and 3.

Survival Instinct2 stacks ATK, Crit Damage, and Crit Rate with each Burst, so raise S2 first. Justifiable DefenseB's enemy-wide attack and Missile Container carry a lot of weight, so raise Burst next. Dreams Do Come True1 only supports explosion range, so keep it low.

She is almost never used in standard lineups. She may come up only for niche uses like experimental Arena 2-Rocket Launcher lineups or Burst Gauge support in Elysion Tower.

Using her Burst multiple times raises both Crit Damage and Crit Rate via Survival Instinct2.
Missile Container focuses attacks on the lowest-HP enemy.
The higher the Survival Instinct2 stage, the greater her Burst's enemy-wide extra damage.

Her Burst Skill reduces all allies' Full Burst duration by 5 seconds.
Reaching max damage requires using her Burst multiple times, slowing team tempo.
As a charge-firing Rocket Launcher, her Burst Gauge contribution is not fast.
Vesti: Tactical Upgrade is the better choice for main damage and Arena slots.

A Nikke from Absolute.