PSA: "free exp" levels
I've seen a couple of these crop up since someone made a youtube video about it.
It's just a whole load of exploding impalers, you hit one and they all go off like a chain of dominoes. This is followed by a suicide booth to give the builder a kill for their troubles.
I'm here to tell you they don't work.
You get the 20 exp from the first impaler you hit, and that's it. No more exp, no currency drops, nothing.