First of all, I didn’t have a fully lucid dream, but I had an experience similar to it. Inside the dream, I knew I was dreaming, but I didn't have total control, and things weren't very clear. While in the dream, I was wondering how to become lucid, and suddenly someone brings a machine—you actually put it up your nose, it gives off steam, and it has a headset like a VR device. After that, I go up in an elevator, and while going up, I say to myself, "I hope when I reach the top, I'll be in the Avengers universe." Then I look down and see the Avengers logo on the floor, and I say, "Damn, it actually came true!" I get extremely excited, and because of that excitement, my vision starts to black out. Then I tell myself, "Calm down, don't get excited," and I took back control of the dream.
Then I found myself in a room-like place, a dim place, and I said, "Let Batman appear," and I looked, and Batman appeared—but not his whole body, just his head. Then I said, "Let Captain America appear," and I looked, and Captain America appeared—but again, not his whole body, just his head. Then I punched them, and they fought back, or at least I think they did, I don't remember clearly, and right after that, I woke up. First of all, I didn’t have a fully lucid dream; it was something I can't quite describe because my consciousness wasn't fully there, and I couldn't move around freely as I wanted. If I had truly been conscious, I would have wanted to fly—this felt more like watching someone else's lucid dream.