I am only just above 600k GP so I am probably wrong in everything I am about to say.
During the event to get her I used her with a Pheonix squad, it may not be the best lineup, but it was so satisfying with all of the counter and bonus attacks. However, it is a zeta for her to assist(maybe it's an omega but I would assume it's a zeta) and it's only against sith when she does so I wouldn't say she's the best for arena, but definitely will be useful for the new raid. I thinks she will be a key component to countering Sion and Treya teams when they inevitably take over the arena though.