Her weaponskills are Dark Flare, Dark Burst, Dark Quake, Dark Freeze, Dark Tornado - they are conal attacks that do sizable amounts of damage.
She summons Elemental Gyves after each use, they can be nuked down fairly easily. They apply various elementally aligned debuffs.
She also has a weaponskill called Dark Moon that causes weakness for a short period of time.
Her one hour is Dark Sun, it is AoE death in approximately a 15 yalm radius. She will say a line before she uses it, so be prepared to run when she is under 50%.
★Maiden of the Dusk
In the first phase she has the same TP move set as the lower difficulties.
On her 2nd TP move and beyond she will get adds (up to 3) that hit hard and (afaik) don't depop even after the first phase ends.
She takes great damage from Light skillchains here.
In the second phase, if you let her get a TP move off it will zero a particular stat for your characters (For example, INT will be 0'd).
TP denial via Absorb-TP or DRK SP2 Soul Enslavement is best to avoid any TP moves from happening at all.
She heals from Light damage and skillchains are a part of this.