Stun Rey. It lands like 99% of the time seriously. Get her health to 55% so taunt doesn't activate. Use a call assist or the highest damage dealer you have to try to one or two hit Rey's 55% health to 0. If for some reason she has a slither of health left make sure you have someone who can dispel RG's taunt. QGJ works really good. Also having dooku helps cause not only he stuns her but his double attack can take off her foresight without knocking her down under 50% health. It's actually really easy. It may take you a few times to get it down to a science, pick arena squads that have Rey and RG. Attack them and use that as practice to help you get better. I've got it down to the point where RG is the last character standing in the group. I can literally kill each squad member right in front his face without activating his taunt. For an even more challenge look for teams that run Rey,RG,Daka,Leia & Sth or Akbar. You have to mix up your stuns for those type of teams cause Daka loves to raise up a dead Rey and RG when the AI is playing you. Not to mention turn meter just makes the challenge more exciting.
I know people won't believe this but the game is extremely closed to being as balance right now. It just takes picking the right squad. Know your enemy. Expose their weakness. Defeat them.
