Just use a off-ele defense KH in sub?
Furthermore I would use my jews for Thunder Aphro instead of dark Amaterasu. She is very situational now. You dont really need her. OTOH Thunder Aphro is still core in DMM if you want a very strong thunder team. However she is limited.
For AoE debuff we have SS, Thanatos, Samael in december and Amon U rework next year. No need for dark Amaterasu.
However I am still not a fan of Amon U next year. She is slow and situational.
Dark has better options: Thanatos(fastest dark KH and covers debuffs) and Cherno (high DATA, hitting like a Truck, strong tank, rage decrease)