[GBF] Light 2b1c OTK Kaguya x Kaguya (On-Element Opus) 

There's probably better grids out there but this is what worked best for me. Opus is on Freyr Chain and Skill Cap. Ultima is on CA Cap(NA DMG Cap might be better).
The plus marks are actually needed. WIthout them the hp is left at around 1-3%
You is on ATK Awakening, Y.Naru is on Multiattack Awakening, Nehan is on Defense (doesn't really matter for Nehan unless you need every bit of damage).
You is irreplaceable.
Y.Naru is replaceable with S.Sturm and H.Mugen. There might be others you can use that I'm not aware of.
Nehan's the reason why this is possible.