Okay, let's get this straight. There's a theory going around lately, and lots of people are agreeing to it.
What if Mabel is the key to "Weirdmaggedon"? The theory has been going around for a while now, more like two weeks. But since this episode has come out, it's been a growing theory.
People are saying that Mabel is the key to this "Oddpocalypse" situation, and here's why:
Mabel is using her imagination, and without her, Bill's plans can be destroyed. We all know Blendin made a huge mistake for getting tricked by Bill, and he was used, to trick Mabel. But, why would Blendin want to get back at Mabel. They freed him, and gave him hair! There's not really anything to get them back at anymore.
The point is, what could have Blendin made a deal to, to get Mabel trapped in a bubble.
But remember this, back in "The Stanchurian Candidate" Gideon even made a deal with Bill. He said in the most recent episode that Mabel was kept in a bubble BY Bill. But what could have Gideon done for Bill in return? Also note, in EP 18, Season 2, Gideon was still in jail before Gompers transformed into a huge building eating monster, and was there reason to break free.
There are multiple questions to ask during the episode, but this isn't the end.
What did Blendin do for Bill, unless he didn't even do anything. We all know how Bill is with his little games and tricks.
But that's what makes Bill, Bill. Without him, this show wouldn't have any foreshadowing, intense plots, and so much more. I think that Gravity Falls wouldn't be the same without him.