WARNING: The following contains spoilers for Season 1, Episode 21, "The Turning Tide" of Digimon Adventure 2020, now streaming on Crunchyoll.
Episode 21, "The Turning Tide," is one of the Digimon reboot series' most jam-packed yet. While Izzy, Sora, Mimi and Joe handle the return of Argomon in The Network, Tai, Matt and his little brother, T.K -- who the boys recently rescued from Devimon's minions -- finally find the location that Ogremon pointed them towards. This spooky tower is also where Skullknightmon places the stolen Digiegg that Angemon was reborn as, and it turns out to be hiding a secret: it's not really a physical place at all -- it's the Mutant Digimon, ElDradimon.
But that's not the only big twist the episode brings. On the brink of defeat in the miasma swamps around ElDradimon's head, MetalGreymon manifests a never-before-seen ability that turns the tide of the battle.
As we've watched each of the DigiDestined's digital friends Digivolve from Rookie to Champion to Ultimate level, one by one, it stood to reason that a Mega form was on the horizon. But, as this new era of Digimon keeps proving, existing franchise fans shouldn't be so sure they know where things are headed.
MetalGreymon's new transformation takes place following Tai and Matt's tailing Skullknightmon to the hidden ElDradimon. Before they can try and enter, however, a Splashmon suddenly emerges from the miasma surrounding the floating fortress -- taking the form of Garurumon, as its unique mimicry ability allows it to do. The result is truly unsettling: appearing less like an exact replica and more like a toothy, Pennywise illusion.
Splashmon is a very slippery enemy indeed, even more so than the serpentine Eyesmon the gang fought tooth and nail to destroy in fake Tokyo. Despite WereGarumon and MetalGreymon's best efforts, both are soon incapacitated by the Ultimate-level enemy's speed and poisonous tendrils. Tai can only watch in horror as Splashmon starts to crawl back into his hiding place, dragging the infected, limp body of his partner with it. Of course, this triggers Tai's Protagonist Power to muscle through anything in the name of friendship -- or more specifically, his Courage Crest. As Tai bravely tries to pull MetalGreymon out of Splashmon's grip, he starts to become infected himself, but his words of encouragement -- reminding his friends of their world-saving duty -- brightens up his Digivice and, in turn, MetalGreymon.
Rather than a full evolution, MetalGreymon instead appears to convert the poison covering him into a brand new appendage: a 'Positron Blaster;' a form that has since been dubbed Alterous Mode. This new blaster, which makes up the entire length of his arm, blows Splashmon away. The post-credits wrap-up even suggests that this arm was originally left deliberately bare (MetalGreymon's slashing Trident weapon takes up the other one) to facilitate this hail mary power-up, as well as teasing the possibility of similar upgrades for the group's other Digimon.
As Tai, Matt, Agumon and Gabumon enter the literal belly of the beast through ElDradimon's open mouth at the episode's end, we can only expect more surprises to come.