Unlight

Unlight was a darkness that could be woven and worn, all-encompassing and past explaining, and it belonged to the primal being Ungoliant alone. It swallowed every light that fell into its path, and the horror and the dread of it were beyond speech. In the Years of the Trees, living in Avathar, Ungoliant spun a great net of Unlight across a large ravine and made her lair within it. When Melkor came to Avathar to ask her aid, she went with him under the Unlight as a cloak, so that nothing marked their approach, and afterwards she drew it over their escape. Its darkness hindered and defeated even the steadfast will of Oromë and Tulkas.