Caloric

Caloric is the name given to the form of energy flowing from the membrane throughout all planes; including the material plane. Unlike heat or electricity, however, it takes a soul to channel this energy into anything useful; No amount of machinery or technology has allowed direct manipulation of caloric without being blessed by, crafted by or, in more grim cases, incorporation of a soul. Spellcasting, magical items, hybrid items, magitech and the likes all rely on a steady flow or set amount of caloric to function or manifest. While it's effects can be described and harnessed by modern science, Caloric has never been directly observed or studied. Caloric was first described, and it's name coined, by a physicist known as Morden, after which Morden's Laws of Spellcasting are named.