I think one of the weirdest fights I’ve had was in a D&D campaign where time travel was a thing. The way time travel worked, “the past” was a very distinct type of period from “the present”. In the past, everything was predestined - things had to work out the way they had worked out before, and if you violated that with your actions very bad things happened. Whereas in “the present” you had free will, you could make decisions and change how things worked out. The difference between the past and the present was simply whether you knew what was going to happen next.

So, we wound up in a situation where we needed to go far into the future and do a ritual. This was really, really bad because if we learned anything at all about what the future was like it would become “the present” and the whole rest of the timeline would become immutable. So before we went there we blinded and deafened ourselves so we’d have no idea what was going on.

Something attacked us. We had to fight back while doing our best not to learn anything about what we were fighting. We never found out how many things were attacking us, or what they were, or why they were attacking. It may have even just been some kind of environmental effect. We have no idea if our counterattacks did any damage. We just flailed around while trying to protect the party member who was doing the ritual, communicating with each other only via telepathy, and then as soon as it was done we time-traveled back to our “home” time.

Years later when the campaign ended the DM offered to tell us about what the heck had been going on, but we were so hardcore about following the “rules” of time travel that had been established that we still insisted he take that secret to his grave. The future had to remain unknown.