Upper-Level is a term used to classify powerful magical beings, such as witches, warlocks and demons. Generally, upper-level beings possess exceptionally strong powers and a high resistance to harm, making it difficult or even impossible to vanquish them.
Some beings are also described as being high-level, but this generally means the same as upper-level. Confusingly, the upper-level demon, Litvack, and the other leaders of the faction he was in, were described as 'generals' of the demonic legions. Their assistants were known as Level 2 Demons in the Book of Shadows. Demons, such as Zahn, can achieve Upper-Level status through means such as soul trading.