All right, I haven't spent much time here in the past decade, so forgive me if this idea's been brought up before, or if there's evidence to shoot it down. But it popped into my head a few days ago, and while I think it's a longshot, I thought I'd throw it out there.
The title pretty much says it all: Could Eldor have been intended to be an older Adam/He-Man who traveled back in time from his old age to Preternia's past? Evidence in favor:
1. The card back leaves his origin unknown, and he's not in the style guide either. Absence of evidence doesn't necessarily mean much, but those are places where you'd expect his origin to be discussed if it wasn't being kept for a big secret.
2. He seems to 'know too much' based on He-Ro's bio from the 87 style guide;
3. He's got a similar color scheme to Adam under the cloak;
4. The cloak itself bears a strong resemblance to the "Preternia Disguise" He-Man used in The Powers of Grayskull: The Legend Begins!.
It's not much, but it's enough to get one thinking. Anyone have more to offer or counteroffer?