Anti-spoiler 

The reveal of previously unknown aspects of a story, except what is "revealed" is misinformation.

Anti-spoilers are a form of anti-joke.

You: "Where are you in the series? Has Hermione been killed yet?"
Friend "Wft dude! I didn't know she dies."
Much later, friend discovers that Hermione actually lives.

. . .
Another example...

"Tyler made me think that the whole story took place inside of a dream, but apparently it was an anti-spoiler. Bastard!"

. . .

Pepper enough anti-spoilers into conversations and you'll no longer be at risk of accidentally spoiling something, because no one will know if they should take you seriously.

Anti-spoiler by Spiral Stardust April 26, 2019

Anti-Spoiler 

When you find out a critical plot element from a movie/game/book, and it only makes you want to see it more, instead of "spoiling" it.

There's a main character switch in Metal Gear Solid 2, two hours in!? now i'm interested. thanks for the anti-spoiler

Anti-Spoiler by young enigma July 24, 2009

Antisoiler 

An individual of incredible attractiveness and moral worth with exemplary standards of personal hygiene, whose presence has the almost supernatural ability to purify the unclean.

Verb = to antisoil.

It became clear to Kris eventually that James was indeed the true antisoiler.

Antisoiler by James February 3, 2004