Octopath Traveler COTC [SEA] : Yan Long Cup 9Turns

Yan Long Cup is harder than any previous cup.

His weakness is Sword, Spear and Light.

He will lock his 2 weaknesses from 3 on the first turn. the slot that opens first is sword then spear then light and go back to sword again. At turn end, he can also remove his debuff, except when he breaks.
Beside from locking, he also gain locking weakness counter. The counter doesn't do damage but will add extra act for him next turn.

After a certain point, he’ll call two Crows to the battle. I'm not sure how much HP has to be reduced, however some have said it 90% HP. Yan Long will become more powerful thanks to the Crows buffs.
(Crows weakness is axe and tome)

After HP's 50% reduction. He will no longer lock his weakness and begin acting 3 times every turn. We need a lot of Def buffs to be able to withstand his attack.

To kill him in 1 break is the best way of strategy. but for now, it's a difficult task. Thus, I try to reduce his HP as much as I can, then let him summon the Crows and kill him once he recovers from breaks with pure strange.