I was able to do it with Luke (It Binds All Things zeta'd), R2 (Number Crunch zeta'd), Baze, Chirrut, and Ackbar. Luke is g12 (none of the g12 gear, though... :( ), the rest are 9 or 10. I think my Chirrut is 8, though.
There's a lot of AoE, but there's enough single target stuff that Baze will soak enough damage that would have killed at least one other character, meanwhile counterattacking and feeding Chirrut's TM and allowing him to cleanse/equalize/mass HoT faster. When Baze's turn comes up he can also clear out those taunts and let you focus on Darth Vader so you don't have that non-stop Force Crush.
In the end, Ackbar wasn't needed--I thought I would need a second cleanse, but Chirrut provides enough HoTs that you'll be fine.
This one's harder than BB-8's Mythic, because that's just a matter of outlasting the initial burst. This one is about limiting the heavy hitters' turns via stuns, speed down, and (if possible) turn meter reduction while also keeping yourself as debuff free as possible. If you don't have the characters I listed above then form your team with that in mind and you'll do better.
