Overview
P90 is a defensive SMG, summoning holograms with her Skill to distract enemies.
P90’s Skill summons holograms based on how many links she has left. If only one link remains, she will only summon one hologram. She also gains some Evasion buffs for a short duration after taking more than 5% of her Max HP or after using her Skill, but these are mostly just bonuses and aren't the main focus of her Skill. While P90 isn’t a bad SMG, her Skill has a rather long ICD (the holograms take almost a full second to appear, meaning her ICD is effectively almost 7s), and only remains active for a rather short duration, making her similar to Force Shielders in use cases.
With her SPEQ, P90 also summons a second pair of holograms after 3 seconds, massively increasing the effectiveness of her stalling, though it still isn’t the best for general content. Her SPEQ-set allows her to buff allies' Crit Damage when the clones die. While the SPEQ-set doesn't make her easier to use, it does make it much more acceptable, as the buffs are quite decent. If you don't need P90, the Set buffs aren't enough to consider using her for, while if you do need her, they're a very nice bonus.
All in all, P90 has a somewhat long ICD, low uptime and enemies that easily retarget will shred through her holograms in no time. As such, P90 is a bit more of a niche pick and is optional to raise.