Then just level your grid, I can't understand why you don't do it.
To steal MVP in high rags you go full damage.
Get that D'Art weapon out and farm Shingen relic.
Let other people do the debuff.
Tbh you have a good team that can clear without problems AQ5/6 but you are just too lazy to level it.
Unless you want to tell me that your fire grid isn't leveled.
You need 8months to have 6 grids at 100% assault+.