I mean, no other episode has made it quite so clear that this series is written for, first and foremost, avid readers of X-books in the 90s and 00s. They did the Big Reveal of the BBEG and...I had no idea who it was. I think I did read some of the comics he was in, at least early appearances, but the pacing and "being clever with shadows" just screamed that the viewer was supposed to recognize him as soon as we saw enough of his appearance. There's still reveals to make in the cartoon continuity (since his origin is unlikely to be EXACTLY what it was in the comics, due to the need to simplify things a bit), but I basically had to pause the credits and look through the character credits to find out who that was. (And if I knew his comics origin before reading spoilered bits in this thread, it would have been from reading an OHOTMU issue.)
Lifedeath I and II also relied heavily on viewer memories of the original stories to flesh things out, but the big reveal this week 100% depends on memories of the original comics to have any impact at all.
---Dave