The opening song was Progeny’s theme. Typically they’ve used it as the outtro music.
The show notes do say this…
We jump right into the story, not wasting too much time messing around as we often do. And! You get to hear hints of some new music! What could this music be? Only time will tell.
The new music is much later on. The music at the start was not new as that’s Progeny’s theme.
No, I know Progeny’s music, I mean the stuff they used as the intro to the main discussion, not the show opening. Sorry I wasn’t being clear. I mean the real dark music with the creepy woodwinds and brass stabs.
I just assumed it was a teaser of Oblivaeon’s theme from the video game.
Something interested me in this episode: during the battle with Borr at Saint-Tropez, A and C evocate « several other europeans heroes »
We don’t know them, right ? Who can they be ?
You know, out of all the amazing information revealed in this episode, my brain would go and fixate on one incredibly trivial nitpick. When Chrono-Ranger is trapped in the past, they specifically say that he’s in Pompeii while the lava flows all around him. If A&C were history nerds, which I thought they were (or Christopher at least), they should realize that when Mount Vesuvius erupted, the lava flowed away from Pompeii and toward its sister city of Herculaneum. Pompeii is the more famous city because it wasn’t engulfed in lava (which would have destroyed all remains and left most of the ruins entombed in solid igneous rock, making an archaeological dig far more difficult); it was instead suffocated in thick layers of ash. Since being in Pompeii would have likely resulted in CR suffocating (and would definitely have looked different in the art, as he’d be buried in snow-like ash and be barely visible), he must in fact have been trapped in Herculaneum instead.
Odds are good that the comic writer in the metaverse didn’t know that, either. 
There are a lot of similar things in real comics, in addition to those in Sentinels Comics.
It must be convenient for C&A to be able to blame their mistakes on an entire fictional universe full of nameless, faceless comic-industry goons. 
Of course, this might not have been a mistake, but an intentional “artistic” choice. Still bugs me either way though.
So this episode gives us a canonical order for the Scions coming out.
- Empyreon (though not yet acknowledged as a Scio).
- Nixious the Chosen
- Faultless
- Voidsoul
- Sanction
- Dark Mind
- Progeny
- Borr the Unstable
- Aeon Master
X. Rainek Kel’Voss (disregarding earlier appearances as Tim Cosing or OblivAeon’s shadowy lieutenant).
Harpy’s spell against OblivAeon is cool because it should be based on actual swarming behavior, the movement patterns that a flock of birds use to evade predators, but drawing the flight paths of all those birds to create a crazy fractal pattern.
Found another possible sequence for the scions, though it’s incomplete. The series Scion Strike appears to have been a six-issue book, and issue 1 is quoted only with regard to Empyreon as far as I can tell. But then issue 2 features Aeon Master, issue 3 is about Dark Mind, issue 4 features both Nixious and Borr, issue 5 has Faultless, and issue 6 is mostly about Sanction. I’ve been unable to find where Voidsoul, Progeny and Rainek fit within that series as yet; I may have missed a card or two from the Scion deck and the ten Scion character cards, especially one or two of their backsides, but I went through most of the 30 quotes involved and came up with this pattern pretty consistently. If we assume that nothing preceded Empyreon and nothing other than Rainek follows Sanction, then we only have two scions to insert somewhere into this sequence, plus needing to figure out whether Borr comes before or after Nixious in the events of issue 4.