Nightmare Fuel / A Hat Full of Sky

• The hiver hides in animals and people, choosing the most powerful hosts it can find, but their minds die. They always die.
  As it went past, it made a noise like a swarm of flies.
  • What makes the Hiver worse is that it lacks any true intelligence, acting on base instinct for most of the book. It's noted that several people fell victim to Evil Is Not a Toy not because they underestimated its intelligence, but rather because it's not sapient and the various countermeasures and contingency plans for other magical beings simply don't work.
• When Annagramma takes hiver-invaded Tiffany to Zakzak's shop, Hiver!Tiffany casually turns the shop's security guard — the young, inept Brian — into a frog. That is, the hiver turns part of Brian into a frog. All of the leftover Brian that didn't fit now floats and wobbles gently above the small frog...
  Zakzak didn’t look at the frog. He was looking at the thing that went 'gloop, gloop'. It was like a large pink balloon full of water, quite pretty really, wobbling gently against the ceiling.
• The hiver killing one of Ms. Level's bodies, made all the worse by the minimal description, and the implication in the next chapter that it basically disintegrated it.
• The moment the hiver takes over Tiffany. She says "see me" to trigger her spell, steps out of her body, looks at herself, starts relaxing because everything is in order... and then she sees her body smile and open its eyes.
  Hiver!Tiffany: We see you. Now we are you.