User blog comment:Adzyn/Tips for RC6 War Demon Shusui/@comment-175.156.211.29-20160103025958

This is obviously late...but i hope it helps when this quest is open again... Based on my personal experience and a little bit of checking guides, Empty Seal (which comes the turn after EoA) can be cancelled by achieving a damage threshold. Thats if you trigger his EoA in the first place anw Checked on a post on reddit which says it can be cancelled by using a UBB, but i still got wrekt by empty seal after using Dolk's UBB. Ark's UBB cancelled it tho, which Shusui will say "Stance has been broken!" on the turn he is supposed to cast empty seal I think he will debuff himself too for that turn. Then, back to normal (stances and stuff)