Abyssal Chain (A.C) and either Sword or Scythe.
I liked using the scythe to get some range throws on her.
If i A.C'd close to her then i would use the swinging over head attack for a nice combo.
When you enter A.C her face and swing a few time.
She will then do a teleport thing, run around in wide circles around the room watching for her shadow.
If her shadow appears close to you or below you dash away quickly.
When she stops, A.C her face and swing a few more times.
Each time you A.C and slash she will get fast with the teleport and will sometimes charge, if she charges, dash and try and get a few hits in from the side.
Sometimes she get caught in a teleport frenzy where she doesnt seem to want to stop. You are going to have to try to hit her a few times even if it means costing you some health.
After a while she will cling to the ceiling and produce orbs, once these orbs float down a little and turn orange, quickly A.C them, and A.C her face.
Watch the cut scene and achievement is yours.