Rosanna: Chic OceanLimited

A Wind Code AR Burst 2 Supporter who applies increased damage taken and increased damage over time at once to push damage-over-time DPS.
Her short Burst cycle earns her a rating as a top Burst 2 candidate in Story, Raids, and special enemy fights, but she has no self-healing or shield.
In Arena, she's only used in limited cases, such as nuker lineups that stack a damage-taken buff onto a single big hit.

At battle start, all allies briefly gain increased Damage to Parts, and whenever anyone breaks a part, all allies stack Increased ATK based on caster's ATK. In the same flow, all allies gain increased Damage to Parts again, and the enemy nearest the crosshair takes damage over time at set intervals. Using her Burst Skill grants all allies increased damage over time and applies increased damage taken to all enemies at once.

Use her Burst Skill while the enemies you need to clear are still on screen. In content split into waves, the increased damage taken doesn't automatically apply to new enemies.
In boss fights with parts, set your firing order before breaking parts so that Ferita1's ATK stacks don't drop.
Manual play is only needed when you time target selection and Burst yourself; otherwise auto is enough.

She often splits the Burst 2 slot with the Blanc and Noir duo. Pick the duo when you need survival healing, and pick Rosanna when you want to raise the firepower ceiling further.

Fit cubes to how she fills Burst Gauge, reload, and ammo for AR Supporter play. If Harmony Cube levels differ greatly, use the higher-level cube before the theoretical ranking.

Elemental Advantage damage and ATK are the baseline. Fit the remaining lines on gear and Overload, such as Hit Rate, ammo, and crit, to AR play.

Onda GrandeB applies increased damage taken and increased damage over time at the same time, so raise Burst first. Ferita1 has ATK stacks linked to part destruction, so raise S1 next. Spina di Rosa2 handles both Damage to Parts and damage over time, so finish with S2.

In content split into waves, use her Burst Skill while the enemies you want to hit with increased damage taken are on screen. Her Damage to Parts increase is effective against bosses with many parts.

A single Burst Skill applies both increased damage over time and increased damage taken.
Increased Damage to Parts and Increased ATK linked to part destruction help in fights with big parts phases.

She has no self-healing or shield, so survival has to come from other ally slots.
With few or no parts, the Damage to Parts increase from Ferita1 and Spina di Rosa2 pays off less.

A limited recruitment Nikke.