That sounds like the Amidala team (MIne is R7 Queen Ami, Padawan Kenobi, Master Qui-Gon, Kelleran Beq, GMY).
Round one you need to use Amidala's multi-shot, but hold the decoy.
Kill 1-2 enemies, then pop the decoy. Maintain low hits on robots until the boss dispells. With any luck he'll do it before you kill his siblings and you'll get a buff with 6 stacks when he removes your Heal over Times.
Next round kill away. During the round you will pop up the multishot -which enables your HoT's- and the boss will dispell, so you get 10 stacks.
Now you can max out the attempt. I get 1.8 million consistently with this strategy. Before? It went from 1.1 million to 450k.
And don't get me started on the B2, Darth Maul, Darth Sidious, STAP and IG-88. I cannot get past 900K 9 out of 10 times.