Gorroth

Gorroth is a mysterious entity in the lore of Dota 2.

Description
Far too little is known about Gorroth, besides it being an authority or tutelary entity of great power since its inscrutable potency is invoked by a certain warlock.

Speculation
Given Warlock's shady background, Gorroth is probably characterized by darkness. Demnok may say "sworn of shadows" or "dark litany" when attacking. Since the only entity that he swears to is Gorroth for its power, then "sworn of shadows" might refer to these "shadows" swearing something as so, with these "shadows" being Demnok and Gorroth. However, it's possible it could be meant for Demnok only and not the Gorroth he consorts with, since the former usually embodies himself as darkness.

As for what "Dark litany" has to do with who or what Gorroth is, "litany" comes from Greek λιτανεία meaning "prayer", which comes from Greek λιτή meaning "supplication". Thus "Dark litany" would be Demnok imploring the aid of someone or something else, akin to him invoking the power of Gorroth. That being said, a "dark litany" could also be Demnok repeatedly reciting incantations to curse his opponent, like a real religious litany where prayers are recited repeatedly.

Also, Demnok usually invokes darkness to bedevil his enemies, so perhaps this darkness he calls upon is Gorroth itself. His spell also invokes darkness, so perhaps his spell is derived from Gorroth too. Lastly, those who are killed by Demnok are sent away to consort with shadows. In conclusion, Gorroth might be a tutelary entity of shadows to Demnok who lends its dark power to him.

Heroes
is the only known hero with a link to Gorroth. Demnok may invoke Gorroth's power as his authority that allows him to do whatever, in this case, mundane walking.