A little bit there is what I'm starting to call George Lucas Syndrome -- "nexus" is used in several ways throughout the publishing history of Marvel. They're... semi-related? But, near as I know, no one has yet made the effort to tie them together.You seem extremely well versed in the comics, so you might be able to give some input here.
In regards to “Nexus” and the in show ad we got, I have read that there is a “Nexus of Realities” in Marvel comics, and it was apparently alluded to in one of the Thor movies.
The article I read said that in some stories, Man Thing is the Guardian of this Nexus.
Do you think it’s possible the vibes we saw in the basement have something to do with that? I’m not really familiar with Man Thing, but I believe he’s...like...a plant?
First, there are Nexus Beings. These are magickally powerful keystone individuals, whose powers affect probability, and, thus, causality. If someone can change reality or rewrite events they don't like, that affects the future. They are watched over by various interdimensional entities and organizations. This is why some are speculating the next Big Bad in the MCU will be Kang the Conqueror. His whole thing is wanting dominion over all realities, all alternate timelines, and using time and dimension hopping to achieve this.
Any given reality only can have one Nexus Being. Some have been on Earth. Others would, obviously, be elsewhere. Most we don't know about and never will. Wanda is one such. What I am less sure about is... Well, she's the Nexus Being in the reality of Earth-616 -- the original Marvel comic universe. I've never seen anything say the same person could, or could not, be the Nexus Being in more than one reality.
Then there is the Nexus of All Realities, and that gets... a little weird. It's a trans-dimensional gateway that allows people to travel to other versions of reality. Very much involved in the Multiverse. All the realities converge there, even though it's in different places in different realities -- and, apparently, sometimes within people. I honestly don't know if sometimes editorial teams get confused between the two types of Nexi.
Any rate, on Earth-616, the Nexus of All Realities is in the Florida Everglades, and Man-Thing is one of its guardians. It was a scientist trying to recreate the Super Soldier Serum. Obviously, it didn't work. He lost most of his human intellect in the process, animal and vegetable matter getting fused through science and mysticism. It can sense human emotion, and, while it fights to protect the Nexus, it is enraged by fear, seeks it out and consumes whatever is sending it out with a sort of mystical-chemical corrosive. The tagline since early on has been, "Whoever knows fear burns at the touch of the Man-Thing."
Between that, Agatha, Wanda, the (probable) Darkhold, the possibility of Mephisto, Doctor Strange and the Multiverse of Madness... I'm curious just how far they're going to go down the magic and horror rabbit-hole of the Marvel universe...