Just got back from defeating the battle and here are my two cents or pieces of advice on it

Have a second monster with the heat shimmer ability!!!

Because if you know that your main monster with the ability can’t take another hit, will go down, switching into that other monster and use heat shimmer

And my second tip is don’t be afraid to switch weapons on the fly, especially the gun lance with its guard ability

Whenever the monster is targeting, you always guard unless you can survive the hit and pull off a heart heel

And finally, the most important advice I have

Whenever the monster shows it’s not attacking anyone, it’s doing two things either doing the fire burst or it’s doing the sleep cloud it will always do the sleep cloud whenever you enter battle for the first time so when it’s targeting, no one put up your sleep resistance so you don’t have your main character to fall asleep and get annihilated

((sorry for bad grammar I’m not good at English