I only have a 5* Rex as well. So this would mean I should just focus on Yoda. I will continue to buy rex shards in the fleet shipments just to get him to 7*. My turn order right now is:
Dooku (197) stuns, Vader (175) force crush to get debuffs for DN, DN (173) uses drain force to increase everyones cooldowns due to vaders force crush, Sith trooper is now taunting, defense up, and retribution, maul (150) AOE daze.
Can I afford to lose those debuffs for DN? I know its still 50% without but the guarenteed cooldown increase is really awesome at the start of a battle. Also, I cant get Maul to be faster than DN, he is just too slow. What would you recommend?