Also remember, Brute Justice is technically a new encounter, so enmity has been wiped completely clean. Blasting the party with an Assize/Medica II/Cure III, Indom/Succor, (Aspec.)Helios right at the start is a sure fire way to glue him onto you until he wastes you or the tanks scramble to take him back.

I know it's tempting to heal everyone up to full after Transformation, but let them get a combo and some OGCDs off first before you heal up. The first brutal attack is Double Rocket Punch which does minimal damage with Virus, cooldowns, and a soak.