NINETY-NINE NIGHTS ACHIEVEMENTS

[XGC Brittany]

Clear Inphyy 100 Points
Clear Aspharr 100 Points
Clear Myifee 50 Points
Clear Tyurru 50 Points
Clear Klarrann 50 Points
Clear special mission 100 Points
Clear Dwingvatt 100 Points
Clear the mystery character 50 Points
Earn A-ranking in all missions 200 Points
Reach the highest level 200 Points

 

[SYN Stallion]

How do you beat the special mission. I have it unlocked I just can't beat the guy with all the health bars and incredibly powerful attacks.