RamLimited

A Wind Code Sniper Rifle Burst 1 defensive Nikke.
She offers an all-ally shield, an ATK debuff, and Burst Cooldown reduction after Full Burst ends when fielded with same-squad allies, but as an SR she's rarely used as a main tank candidate.
If the same-squad condition isn't met, she doesn't get the Cooldown reduction benefit.

Using her Burst Skill briefly shields all allies based on the caster's final max HP. Landing normal attacks a set number of times applies an ATK reduction to the target, and when Full Burst ends, if a same-squad ally is present, she gains Burst Skill Cooldown reduction. Sister's Authority2 applies only increased max HP to herself and gives Increased DEF based on the caster's DEF to the two allies with the lowest remaining HP.

Fire after reaching Full Charge to keep normal attack hits going.
Use her Burst Skill when allies need a shield.
If you're aiming for Burst Cooldown reduction, put a same-squad ally in the team and time when Full Burst ends.

Use Reload and Max Ammo to line up her Sniper Rifle Full Charge and reload pattern. If the cube level gap is large, use the higher-level Harmony Cube first over the theoretical ranking.

Set Elemental Advantage damage and ATK as a baseline. Her shield scales with final max HP, so building DEF and her own HP through gear increases shield values. Add Hit Rate to land debuffs.

Her Burst Skill handles the ally shield, so raise Burst first, then the active with the ATK debuff and survival buff.

She adds survival support with shields and DEF buffs. Without a same-squad lineup, it's hard for her to get Burst Cooldown reduction.

Her Burst Skill shields all allies.
Landing normal attacks applies an ATK reduction to the target.
If an ally from the same squad is present, she gains Burst Cooldown reduction after Full Burst ends.

As a Sniper Rifle, she Fills Burst Gauge only at a modest pace.
As an SR defender, her stat ceiling and buff level are limited.
If the same-squad condition isn't met, she doesn't get the Cooldown reduction.

A collab-limited SR.