Enochian is a name often applied to an occult or angelic language recorded in the private journals of John Dee and his colleague Edward Kelley in late 16th century England. Kelley was a spirit medium who worked with Dee in his magical investigations. The men claimed that the language was revealed to them by angels. The language is integral to the practice of Enochian magic.The language found in Dee and Kelley's journals encompasses a limited textual corpus, only some of it with English translations. Several linguists, notably Donald Laycock, have studied Enochian, and argue against any extraordinary features in the language.Dee's journals did not describe the language as "Enochian", instead preferring descriptors like "Angelical", the "Celestial Speech", the "Language of Angels", the "First Language of God-Christ", the "Holy Language", or "Adamical" because, according to Dee's Angels, it was used by Adam in Paradise to name all things. The term "Enochian" comes from Dee's assertion that the Biblical Patriarch Enoch had been the last human (before Dee and Kelley) to know the language. 
The language used by demons: Edit
Demons use this language to obtain powers or negative energy, and many also do meditation while saying this language. By doing this these beings obtain more negative energy in the area, and cause positive energy brought out by Christians and other people to diminish.
 The Wikipedia Article about Enochian keys.