I don’t have any ranged units. Don’t not like gunners so I will probably Save for her. She’s slow but has a time mage sub. TMR looks very good for evade builds. Time mage sub makes for a very good secondary DPS. Also perfect use of tetra esper here.
She was in the meta in the top tier guild wars in JP for the previous map. That time mostly team consist of Agrias, Ilydra and Nivlu. She is great for killing Ildyra which is still one of the most used healer there. Currently in JP guild war most team consist of tanks are WOL, Kilphe, Agrias, Rain. Healer mainly Ildyra, ayaka and halloween leela now. Damage dealer Kain, Nivlu and Sakura.
I would suggest you pulling for other units instead of Nivlu if you already have Frederika. Frederika still does have its strengths like barrage, reflex and sharpshoot and should be sufficient for killing or hunting Glaciela and Ildyra.