What if you took the vocals from Metallica's "One" and put 'em on top of the instrumentation of "Countdown to Extinction" by Megadeth? You'd finally have Dave Mustaine and James Hetfield reuniting for sure, but then you'd also have the abomination that YouTuber The Taskmaster has created.
I think it's the pitched down Hetfield vocals that are really getting me on this. That, or I'm totally thrown off by having not Mustaine sing over Megadeth riffs.