(spoilers for The Oldest View!)

The Rolling Giant is so scary because of how it tricks him into thinking it's a weeping angel type monster but then at one point just starts rolling towards him at full speed while he's looking at it

Horror antagonists/monsters tricking the main character into thinking they have the upper hand and then revealing themselves to be much more powerful than they let on is one of my favourite things ever because it's so petrifying, that sudden feeling of complete fear and powerlessness