With this current team, I can usually drop him in about 6 to 7 mins using warcry on Catastrceros and spamming bellybuster and bowlder. Using a few sprite dews (gotten easily from rank C at the Solosseum) and 1 nostrum (from rank A at the solosseum). and the occasional upsy-daisy, the battle is not that tough. Just really need to avoid his "Beam attack" and everything works out.
PS: It would have been great if they had a save point in that forrest area where he is to speed things up a bit.
Your Swain, Bone is for your Swain, and Bone is good, he will out DPS your current three, you can spam the two single target skills with no cooldown, or you could just leave the AI to do it if you are not worry about speed. --- PSN: zhi_long
A catastrocers/demoliceros on each party member, war cry-> belly buster+bowlder/haymaker spam, set AI to "give it your all", take like ~5 min to take him down --- Where is heaven? Above the sky, and below your feet.