BRUH... wtf are you doing ... so many mistakes...
First: you use Pluto's assault+ele atk buff if you are going to burst and not for skills... thats... common sense... it has 8T CD...
My dark team bursts Turn 4 already, sometimes 5.
Second: Satan debuffs first --> and then the other debuffs...
Thrid: Get Shingen. Because you got already those fast dark KHs and Shingen has better synergy with dark. Tbh I would kick Amon U from the team and replace her with Hades/Osiris/Cherno or Berith (next month release).
For light it depends imo, if you want to use Shingen and main light next year and be OP+fast.
Then you will need at least 3 MTix if you are unlucky... (Micha AW, Lugh/Take, Tish and Iris)
Currently for that set-up Herc is fine and the best solution to give that immortal element somehow more damage.
Shingen will be too fast for light currently, thats going to change next year.