I was playing the game on a casual 100% run just now and accidentally got the quick-kill. It wasn't triggered how you normally would either. I can't explain what happened clearly, i wish i had recorded it. I had triple pike ball on, and was whipping nega-shantae and the quick kill triggered when she ran into me. No immunity frames or timing. In theory, I either hit her as she hit me (keeping in mind there were no immunity frames), or I hit her the same time as the pike ball did, or I whipped her + piked her + she hit me all at the same time. It was quite odd, especially since i was trying for the old fashioned kill.