My idea for a monster was (I haven't read it all but hopefully this is quite unique) But basically how this monster works is that it's slow when there is light and friggen fast when its dark(basically teleporting when it comes to coding, so implementing this monster would be quite difficult, in terms of making it work in the right environment). So if we imagine a scenario with this monster, we see a long hallway with light close to every door in the hallway, but between each door there is a shadow in which the light cannot reach. When you enter this room you see the monster at the end of the hall way and it starts to slowly walk towards you but it's really slow, when it finally reaches the shadow it instantly "teleports" to the end of the shadow so you can see it once again in the light walking slowly.
Horrible drawing if I explained it poorly:
--- = Shadow
[Light] = Light
You---------------[Light]--------------------[Light]--------------------[Light] Monster
So everytime he walks into the shadow he teleports to the next light source looking like he always walked slow.
I hope you see what I'm trying to say here. I sure know I would shit myself if someone managed to pull this off.