Most impressive feat obviously is Shanks one shotting Kid + Killer at the same time. After they faced Kaido/BM, and Kid played significant role in BM's defeat while tanking attacks from her
As for impact....base Kaido bliting and one shotting Luffy for sure, after no selling every single attack from him. That was one of the most brutal displays of overwhelming defeats I have ever seen in OP, certainly in post TS for sure.