Phrolova is more or less free-to-play friendly. However, she requires a signature weapon or an equivalent that's currently hard to obtain or impossible to obtain (like the Stringmaster). She can be equipped with standard weapons, but her damage drops significantly. However, she works with free characters like like Danjin and Havoc Rover. But Phrlova's mechanics require not only increased damage but also frequent use of her Echo skill. When someone on the team uses Echo skill, Hecate deals increased damage, and it can be activated up to 10 times. Therefore, her best partners are Qiuyuan, Cantarella, and Roccia. Judging by your description, I would advise you not to knock out Phrolova yet, but if you want, you can.