Tldr: She's Robella for a good element. The greatest most spamable cleanse/heal skill in the game for gun smoke, nice debuffs with def down being the most important, very good buff but keeping it up for more than 1 dps is a pain unless you have v3, but even then it's not needed, the summon sustain is free because all her skills have no cooldown or skill point cost even.
You might accidentally kill your own units if you aren't careful with the buff because it does eat a lot of hp from units with a lot of extra actions, just use it when you have Springfield's ult up and it won't be a problem.
She won't out perform a borrowed Klukai but she can definitely held her own if you have an invested Springfield and Nikketa. If you want to invest more into her then she can do very nice damage but I still think keeping her at v0 and investing into other units like Nikketa and Springfield is better. Overall a nice unit but a bit limiting at low dupes.
V3 and V6 are the most important dupes, she can start to do decent damage at v5.
It's very expensive to build her and there's better units to heavily invest in anyways. Weapon choices are between the signature, Faye's standard weapon and the battle pass weapon, if you need more damage get the standard weapon and if you need more utility get the battle pass one.
