mmm.
I've actually spent a large amount of time figuring out how the character could really set her two personalities apart (since she's decided to join the JUSTICE LEAGUE, where all of the heroes are, which is both the safest, and most dangerous place she could go.) No hero would believe that a villain would be stupid enough to become a real, devoted, non traitorous hero.
There are two personalities: Annabelle Cain(Cousin of Cassandra Cain, daughter of a notorious killer)/Scorn (Malicious) and Mana Nimue/Hex(Benevolent)
The only powers Scorn is shown having is dark magic, energy draining, bladework, instant personal teleportation, and a scream that causes people to get disoriented and bleed from their eyes. She fights like a trained killer, and mostly just melees targets to death, draining them as she does. Given enough time and enough luck, she could potentially kill superman, but that would involve at least ten minutes of total draining, which would be enough time for backup to arrive.
The powers Hex is shown to have is Elemental abilities (Fire, Ice, Electricity), energy draining, multi-person delayed teleportation (runic sigil with a cast time) and incorporeality (Can't wear armor, but nonmagical, non-treated weapons pass right through her) and fights like she's never gotten into a real brawl before. She mostly just hurls bolts of energy at targets from afar, and when in doubt, knocks targets back and flees. She is seen draining targets, but mostly to stop them from using powers.
Both of them can't eat food, digest food, and regenerate extremely fast. Also, when they get mad (which Annabelle is doing constantly, but Mana usually isn't), their eyes shift from brown to solid black (no color in eye, all black.)
They also can't wear armor, due to incorporeality side effect.
Also, the person that killed her was Deathstroke.
Yknow. The dude in red from Teen Titans. The bastard that never fails a contract.