This just gives a general idea of how Dralgorog is supposed to look.

Dralgorog is a demon made of abyssal darkness, darkness itself condensed into an ominous tar-like slime. Dralgorog has a head adorned with a gloopy beard and three sets of horns, two sets of horns attached to his body, two arms also attached to the demon's body, and glowing blue eyes.

The Darkness Gloopiness is just meant to show that Dralgorog is really gooey looking.