Juiblex can fly/float, and flow under doors. He in amphibious. He has no head. He can see invisible creatures. Juiblex is acidic and poisonous if eaten.
Little is known about the Faceless Lord, even the correct spelling of his name. He does not have a physical form as we know it, and those who have peered into his realm claim he is a slime-like creature who swallows other creatures alive, spits acidic secretions, and causes disease in his victims which can be almost instantly fatal.