Rumani

In Arena she's rated as a top Burst 1 tank, but she's almost never placed in main slots for Story or Raid bosses.
Her taunt and durability fit Arena, while her healing and raw firepower don't meet PvE main expectations.

Each Full Charge attack stacks Muscle Up1, a max HP increase, for a short time.
During Full Burst Time, Full Charge hits taunt the target.
When multiple shots hit the same part and the cumulative hit count is met, all allies briefly gain increased Damage to Parts.

Using her Burst Skill grants herself a max HP increase and gives all allies an increased normal-attack damage multiplier.
When Muscle Up1 is at max stacks, she briefly gains Damage Taken reduction during that same Burst window.

Land Full Charge shots to build Muscle Up1 stacks, then use her Burst Skill.
While Full Burst Time runs, apply taunt with Full Charge hits, and if there are parts, hit the same part repeatedly.
Leave her on auto by default, but time taunts manually.

For Burst Gauge rotation, prioritize the Quantum Cube, and consider the Resilience Cube for Rocket Launcher reload support. If Harmony Cube levels differ greatly, use the higher-level cube before the ranking.

When maxing, lay down Elemental Advantage damage and ATK lines, and add more Charge Speed lines if Full Charges make up a large share.

Muscle Up1, Muscle Time2, and Muscle Almighty split defense, parts buffs, and Burst buffs between them. Only raise them to 10 if you use her heavily in Arena; otherwise you can stop at the value range.

In Arena, she aims for a Burst 1 tank, taunt, and short buffs. In PvE firepower-focused stretches like Story, Raid bosses, and Tower, she's hard to justify in a main slot.

Her weapon is a Rocket Launcher, so Burst Gauge fills quickly.
Full Charges stack Muscle Up1, and her Burst can add max HP, an ally normal-attack damage multiplier, and even Damage Taken reduction as backing.
During Full Burst Time, Full Charge taunts and a parts-hit-based Damage to Parts buff serve as squad support.

Raising her max HP doesn't make her sustained healing large.
She falls short of PvE single-target firepower expectations.
Reloads, shot grouping, and charge management are a burden.