D: Killer Wife

A Fire Burst 1 sniper supporter.
She reduces allied Burst Skill Cooldown and grants an Attack Damage increase through Full Charge conditions, speeding up the squad's cycle in long fights.
Aiming the sniper and positioning the Burst mark yourself is a heavy burden.

Landing five Full Charge attacks grants all allies an Attack Damage increase, and eight reduces Burst Skill Cooldown for all allies. Three Full Charges give her one Pierce-specialized round, and when Full Burst Time starts, all allies wielding Sniper Rifles gain a Pierce Damage increase. Her Burst Skill deals additional damage and Target Annihilation to the enemy nearest the crosshair, and while the mark is up, allies gain a Core Damage increase for hitting parts and Increased ATK based on the caster's ATK for hitting the body.

Keep chaining Full Charge shots to meet the ally buff conditions.
When Full Burst Time starts, set the order so Sniper Rifle allies receive the Pierce Damage increase.
To align the Burst mark position and Full Charge timing together, handle crosshair, Charge, and reload manually.

Reload and Charge Speed cycle the Full Charge count conditions quickly, and ammo-refill cubes increase your shot count. If Harmony Cube levels differ a lot, use the higher-level cube ahead of the ranking.

To meet the Full Charge count conditions naturally, tune Charge Speed and ammo together. Cover Hit Rate with gear and leftover lines.

Many of the Full Charge count conditions sit on her second skill, so raise the second skill first, then the Burst and first skill.

With Sniper Rifle allies present, the Pierce Damage increase applies at the start of Full Burst. In long boss fights, Burst Skill Cooldown reduction and the Attack Damage increase cycle frequently.

She can reduce Burst Skill Cooldown for all allies.
During Full Burst Time she grants a Pierce Damage increase to all allies wielding Sniper Rifles.
While her Burst Skill mark is up, core hits and body hits grant a Core Damage increase and Increased ATK respectively.

Her Burst Skill mark locks onto the enemy closest to the crosshair.
Meeting the Full Charge count conditions takes ammo and Charge Speed tuning and a lot of manual aiming.