Im sorry but the nun fight is absolute fucking garbage.
No matter what i try, my full level 40 team cant do shit. She keeps healing and healing while slowly killing my team, constantly. Fuck this fight.
Well its not that hard as you can grow 2-3 characters before it. If you do that it will be very easy - just kill the nuns. They are going to get nerfed in the next update so it will be much easier then.
I made it that hard as with it you kind of enter the 'endgame' of the current version, so it can't be so easy.