WARNING: The following contains spoilers for Episode 46 of Digimon Adventure 2020, "The Sword of Hope," now streaming on Crunchyroll.
As promised by the last episode's preview segments, Episode 46, "The Sword of Hope," reintroduces Digimon fans to Angemon's Ultimate form, Holyangemon (also known as MagnaAngemon). The archangel's emergence, as the episode title suggests, comes about by the Champion-level Digimon fighting to retain his faith after being confronted by his past demons -- or rather, one specific demon, Devimon. While the villain isn't resurrected in the Digimon reboot series proper, his repeated presence is no less chilling for the Holy Digimon and the Chosen Ones. In fact, even when the fallen angel is defeated, it's made clear that a piece of Devimon will forever haunt Holyangemon.
Devimon's return is made possible by Sephirothmon. Older viewers may remember this many-balled foe from Digimon Frontier, in which it worked as a servant of the evil Cherubimon. Here, the Hybrid Digimon is a lot less Shakesperian in its battle patter (the mouth orb keeps its distance) but still decidedly creepy as a collection of silent, green blobs with eyeballs. Its strategy involves abducting the kids -- Matt, Tai and T.K, along with their Digital partners -- and then forcing them to fight past enemies by reading their Digimon's battle data and replicating said enemies, creating a kind of chaotic tournament world that also functions a little like a clip show episode.
In the case of Angemon, Sephirothmon's reference point is actually a struggle between the two that took place much further back in time, before Digimon Adventure 2020 even started. We already knew from previous episodes that the Chosen One's Digimon fought in a war against the forces of darkness long ago, and that the Holy Digimon were also a key part of this, but this is the first time we've learned the full extent of Angemon's personal history with Devimon.
Devimon is the Lucifer of the Digimon mythos, created if an Angemon falls from grace into the distorted parts of the Digital World. The evil incarnation is part of every Angemon's evolutionary line, and T.K's partner's fear of succumbing to this fate is made 'real' by Sephirothmon's replication powers -- turning Angemon, temporarily, into a twisted, many-eyed corruption of his former self.
His bond with T.K, holder of the Crest of Hope, eventually cuts through this evil spell, and his jump to Holyangemon packs enough saintly power to cut the Sephirothmon orb to ribbons from the inside. Being a creature of disparate parts, this isn't the end of the analytical villain, who appears to be working on Milleniummon's behalf. The episode's end also leaves us with another interesting sting: as Holyangemon basks in its victory, the voice of Devimon whispers to him from his blackened left arm, creating a real devil-on-the-shoulder motif, and seeding the possibility of the dark Digimon either reemerging properly or perhaps influencing Holyangemon in future fights.