I had an idea for a new hazard which could be found in....
All Jigsaw Valley levels.
All Compound levels.
Possibly Wolver Dens.
Gloaming Wildwoods/Ultimate Gloaming Wildwoods.
These Buzzsaws would be found in groups of 2-4. They follow a long metal-like trail and go back and forth, left and right (depending on which way the metal-like trail is). This trail is a straight line, they are either horizontal or Vertical, not diagonal. You can walk over the trail and the buzz saw goes average speed, considering that there are a few at a time all near eachother. You cannot destroy these Buzzsaws, and they do not damage any monsters, even Lumbers!
I put this idea in one of my last posts however I added it along with a new Arcade level so no one really checked it out. That's why I'm putting it as it's own suggestion here. (Sorry if this is considered 'spamming'). This idea has also been changed from my other one slightly, as these now deal pure Normal Damage, my old thread said they did Piercing, but it is now Normal.
Shankles, wich in turn come on every damage combination. There's one clocwork tunnel variation where they spawn just like this.