A small error in the production of JoeCustoms member bithomas’ figure set has revealed that Darklon is most assuredly one of the as-yet-to-be-revealed G.I. Joe Convention exclusive figures, most likely part of the IG Ground Assault 2-Pack.
JoeCustoms member bithomas accidentally received the filecard for Darklon in his 15 figure boxed set. If these filecards were produced, then that can only prove that Darklon is certainly involved somewhere. Check out the mirrored image below, again from JoeCustoms.com: