Yog-Sothoth is thoroughly indescribable and unconcievable, way beyond human comprehension, and those in his presence can only perceive an approximation. But most notably as a mass of glowing orbs that continuously merge, regrow and break apart, with eyes or tendrils in some versions. He is an unfathomably powerful deity and one of the most powerful of the Outer Gods, he's the embodiment of all reality and the continuum size and intelligence, equal and possibly even superior to Azathoth himself.