There are plenty of Elden Ring challenge videos where people defeat bosses without getting hit, but this new escapade is all about beating every big bad, including the DLC fights, with a one-hit KO.
Streamer, YouTuber, and overall Elden Ring expert Bushy thoroughly explains how he competed this challenge in a five-hour long video that's been cut down after over 50 hours of streaming – 54, to be precise.
As you'd expect, it includes an absurd amount of set-up and also a fair bit of luck. One caveat you need to be aware of is the one-hit rule actually means one attack per enemy health bar.
This seems fair since there are a lot of bosses with two which would actually be impossible to beat in a single shot without some sort of glitch.
As for the attacks Bushy can use, "anything that requires one single button input," which includes chargeable spells, but not continuous ones like Comet Azure.