Which Fjorm?

Even though Fjorm really wants that +ATK, the -SPD is not worth it. The second one is way better

Fjorm has 2 ways to build, and they both involve +Atk to help her secure kills. If you go -Spd, I’d recommend a steady breath/quick repost/aether build. My personal favorite is the -Res: life & death ice mirror combo.

I don't like -spd on her, but it's a matter of taste. I think there is validity to that school of Fjorm. She will need to tank very hard, though.