Tanking tips for Tangata?

[TheTen]

I just ran Halatali as a MRD for the first time (I've always been LNC/DRG before), and I had trouble with the final boss Tangata.

When the boss became invulnerable, I backed out of the fire around it and tried to help with the fire sprites, but that meant I lost hate, and once the boss was vulnerable again, no amount of Flash and Overpower could peel it off our healer.

Am I supposed to stand in the fire and let the healer take care of me? Is there some trick to keeping hate? Any tips would be appreciated.

(We defeated it, but that can't be the way it was intended.)