I don't recommend using a Sentinel because his -ga spells can get 2 or even the whole party caught in the blast, which will give you a lot of troubles with healing.
If you deal damage fast enough, you should be able to kill at least 2 heads before he starts casting -ga spells, so you can wear a lot of fire resist accessories and leave the fire head for last, or whichever element you prefer with the corresponding accessories.
You may want to use a Scanner as soon as the fight starts so the AI won't use the wrong elements; every second matters.
Of course make sure to have 3 TP so you can use Odin as "oshit" button should you not be able to deal enough damage when Destructo's countdown starts.
P.S. How are people going 1/1 on this boss on their first playthrough without healing? Overgrinded much?