In issue 31 of the London Editions UK He-Man comic, we get 3 stories tell the tale of Extendar and Dragstor. 

My Friend No More, Battle of the Fright Zone and Dome of Doom. They were reprinted in later issues, Adventure Magazine. 

Extendar and Dragstor were the best of friends until they were captured by Grizzlor and the Horde and turned into cyborgs by Hordak. 

https://he-man.fandom.com/wiki/London_Editions_-_MOTU_31_(UK_Comic)

There is a new mini comic that comes with Extendar, Terror of the Technomancer!, which you can read in the YouTube review of the figure from The Man Child.

https://he-man.fandom.com/wiki/Terror_of_the_Technomancer!

SPOILERS BELOW FOR THE COMIC

Dragstor does appear in the comic. The comic ends with Hordak creating a new Dark Warrior that we only see in silhouette. The head of the character does not look like Dragstor in any way. 

https://imgur.com/a/OfZiAsk

Do you think this is Dragstor? Who Do You Think This Is?

After spending a day or more thinking about this, and seeing several people say it's Hordak or Horde Prime, when I posted this to a couple groups on Facebook...

My theory is this is going to be a brand new character, or mostly new character. The MOTU Origins action figure will reuse the Extendar arms and legs, maybe in a new color, the body will probably be the reuse of some Horde body, with a new head.

That's my guess. What do you think?