That’s my guess. My headcannon is that the card depicts some sort of duel betwixt two different alternate Drakes. (Possibly in the Realm of Discord?) The Rainbow Rhythmist looks like he has some kind of smug, almost-villainous grin, while the Monochrome Mandolinist doesn’t look very mean, so I almost wonder who’s supposed to be the villain or the hero.
Alternatively, the grey guy might be the Silver Sorcerer, the Adept from the Inversiverse. Or, perhaps instead of being a Virtuoso of the Void, he’s a Guru of the Grey.
The problem with Dark Visionary—or Mr. Jitters, as @Thunderbird mentioned—is that, I think, neither of them can really create monsters to do their bidding as the Dreamer can. Dark Vis has mainly the same powers as her good counterpart, while Jitters simply manipulates fear.
Regarding Æternus, it seems odd to me that the Æ effects are just signalled by that letter, rather than a symbol, word, or both, like Exterminate/Fabricate, Perform/Accompany, Infected, and Ammo.
Also, Shoulder “Advisor” is great, especially Guise’s quote. XD One of you Patræon folks should put Writers’ Room: The Guise Book #11 up for voting.
From O-X’s update, Unity’s quote on Production Processes is also great. Unrelatedly, the quote on Paracausal Shielding is listed as being from Omni-X, while the quote on that card’s EE counterpart (Temporal Shielding) is from Tachyon, despite being the exact same quote. Is this the first time that the speaker of a quote has been retconed?