I want to expand my monster repertoire. Recommend me some monster books, with interesting/unusual/rarely done monsters, high CRs (minimum 10) and interesting statblocks (I can do a huge blob of HP that bites once a round myself). If they're not on 5etools please give hints on how to acquire them.
If you have high CR homebrew monsters (or low CR but with interesting abilities that could be adapted into high CR), do share as well please.