Zeta advice for arena

Hi! I would go for "Insight".

Insight makes her basically unkillable except for fracture.

My vote would be for combat analysis. Helps the entire team, not just RJT and gives the same basic ability that Insight does (on crit instead of immediate, of course) but also to the entire team.

I forgot to mention that the other two will probably be gk and fost (but not really sure about that yet)

I would advise against FOST unless you have no better choices. He has absolutely no synergy with your other characters and doesn't really provide you any benefit other than another taunt. There are many other taunting characters (if that is what you want for this team) that you could choose from that would offer better synergy and viability. Just off the top of my head.....Old Ben, Chopper, Baze, K2SO, STHan, Poe, Chief Nebit. Even Paploo would be a better choice in my opinion.

I want to use him for his assist when he uses an ability. Also he and gk are my best geared tanks atm.