This raid need teamwork.
First you need 3 people to hit a gate (right,top, and left)
For BOSS hitter i think CannonM is the best in here because his talent damage incrase by combo.
Also u need is some one can do Holy Guard (BowM or CH) so your team mates not get freezing from BOSS or you can bring AxeM so he can immune from frezzing skill.
If you want to incrase damage by your hitter you can bring Calestial Hunter for debuff with Hunter's Mark or AxeM with Freezing Axe or another CannonM with Deep Insight.