TIMEQUAKE
Running from What If...? vol2 #s 35-39, "Timequake" was a unique storyline that featured a threat to all of time across all realities.
The storyline spanned various alternate timelines sequelizing several previous issues of the series, specifically What If...? vol 1 #1 (Spider-man joins the Fantastic Four, based on ASM vol1 #1), What If...? Vol 2 #19 (Vision conquered the world, based on Avengers vol1 #254), What If...? vol 2 #24 (Wolverine Lord of the Vampires, based on UXM vol1 #159), as well as a new What If...? based on Thor vol1 #400, and cameos from a number of other issues/alternate realities.
Along with the Watcher, Timequake also heavily featured the Time Variance Authority, a bureaucratic group of timeline monitors that first appeared in Thor vol1 #372, and was in part an homage to legendary Marvel writer/penciler/editor and master of continuity Mark Gruenwald, whom all the TVA executives looked exactly like. Of note, the sneak peek for the Disney+ Loki series has a shot of him in a prisoner jumpsuit labeled "TVA"...
Timequake was an exceedingly ambitious storyline that I very much enjoyed, with an odd "twist" ending. I wish they had tried that sort of thing again in the pages of that comic, though the events of Timequake were later referenced in Avengers Forever.
