Gear for 510+ ACC, request people with Thunderstruck run away from the boss rather than strictly to the rear (seriously, no need to go to the rear except for the Lunar Dynamo one, no one but the Thunderstruck guy + melee should be moving Fire 2 and Fire 4 anyway, and Fire 3 everyone should be spreading out), and just try to sneak in what positionals you can when you're forced to stack for Thermal or Fires. DRG does pretty well in the final phase if you can keep your rotation going rather than settling for the safe positionals only.