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The image of Daoloth was not shapeless, but so complex that the eye could recognize no describable shape. There were hemispheres and shining metal, coupled by long plastic rods. The rods were of a flat grey colour, so that he could not make out which were nearer; they merged into a flat mass from which protruded individual cylinders. As he looked at it, he had a curious feeling that eyes gleamed from between these rods; but wherever he glanced at the construction, he saw only the spaces between them.
~ EXP: Ramsey Campbell , "The Render of the Veils"

This subject contains information from the Expanded Cthulhu Mythos, and not based on H.P. Lovecraft's works directly. Daoloth (The Render of the Veils or The Parter of Veils) dwells in dimensions beyond the three we know. Worshipped on Yuggoth and Tond, and formerly in Atlantis, his astrologer-priests are said to be able to see the past and the future and even how objects extend into and travel between different dimensions.

Daoloth's indescribable shape causes viewers to go mad at the sight of him; thus, he must be summoned in pitch-black darkness using the Daoloth formula, and is known to take a small amount of blood from the summoner. If not held within some kind of magical containment, such as the Pentacle of Planes, he continues to expand and expand — perhaps even at an infinite rate. Those enveloped by the god are transported to utterly bizarre and remote worlds, usually perishing as a result. Daoloth's worship is rare on earth.

One request that can be made to Daoloth, magically contained, is to view things as they really are, not as our veiled senses perceive them. The sight is usually more than one can bear.