You can hit -35% Atk/ -50% Def debuff with your actual team though Triton's and Cthulu's A frame Atk debuff are being redundant to each other.
The change depends on what Kamis you have on hand and what build you're aiming for. My best build would be as mentioned before:
- Mordred (sniper shot) + Sol + Shiva + Cthulu + SSR Nike [-50% Atk/Def debuff +40% Atk/ +20% Def buff]
Late game:
- Shingen (Black Propaganda OR Fortune) + Sol + Snow Raphael + Cthulu + SSR Nike [-50% Atk/Def debuff +20% Atk/ +20% Def buff]