Re: The Deceiver's Double
I know you don't like letting go of a theory until someone provides incontrovertible contradicting evidence, but in this case that's impossible, isn't it? I disagree but I doubt I'll be able to convince you.
For whatever reason they decided to say in GURPS that the D is still alive, which means he has to survive Shiver's death. Okay, we watched him get blown to smithereens. Does this mean he was a double all along? I don't think so. Maybe he wanted to fake his own death so he merely teleported out at the last second and teleported some Myrk guts to where he had been standing--who's going to bother id'ing the resulting mess? This seems more likely an explanation to me (okay--go ahead and open that level in Loathing, find out that yes, those are Deceiver parts--it still doesn't say "Deceiver Double Parts", does it?).
As for him not having his full powers in the game (the same way Shiver appears not to have hers, even though that spark attack is definitely called a "whisper dream" in Fear), I think that's just a gameplay issue. They are not different powers, notice, just weaker than you'd expect. Well, if he could charm an entire army of maul with one quick spell and cloudkill another army of thrall at the same time... how fun would that be (after the initial giggle factor wore off)?
Finally, if it's just a double frozen in the ice, then why would the scepter work on it? Surely it's the real scepter--and it would definitely be attuned to the Deceiver himself and not a hurriedly-chosen lookalike. It doesn't give the zerk the power to charm or cloudkill... your theory about the D using his powers long-range is interesting, but in the end I think it's a cop-out. If he could charm just one shade from half a continent away he could still do in most of the Dark in an afternoon.
Oh, and btw, if the Deceiver's been running around free for sixty years, what's he been up to? He doesn't seem like the kind of guy to me who'd take a six decade vacation, not while SB and Shiver are still standing upright. Not to mention those missing Fallen Lords whose fates are unclear...