Concept: “Inside you will find eleven unclean rituals to soil your game, written by Harkast the Alchemist himself as he roamed the tombs of Graven-Tosk.”
Content: A grimoire of eleven dark rituals from a miserable, dying world. 
Writing: Obscure and meticulous rites of ruinously specific purpose.
Art/design: Diagram’s and illustrations of unclean rituals and materia.
Usability: Technically not powers.