Dojo Soling

So, as people have been saying, this would be a godly area to be leveling up and such, but i must be missing something here. Even when "buffing" the rate that the charge happens by lowering my HP at something weaker like Blue MM, and using invincible at Manon and Griffey and Levithan, i cant seem to get past them. Normally Id just end up dieing at Manon, or griffey if im lucky to get past, but it really doesnt seem like this is plausible as a training method.

So am I doing it wrong? any pointers?