Inspired by a challenge on Elysian Fields Spuffy Archive, this tale mystical education and Elizabeth Summers ascertaining how to use blessed objects in general and one in particular: Consecrated Hosts to fight against Preternatural Monsters, one of her instructors in this is William Pratt. Don't worry, this won't involve badness, but will have to do with what might be called "preternatural biology" for lack of a better term.