The Magi depicted on the Robe of Ancient's card is Agram's brother Padram
Look, the blueish hair, dark brown skin? Dude kinda looks like Rayje. And who is Rayje the younger spitting image of? Agram. Une's spirit is in the Book of Elders
So in Cage of Daylight we learned that Une undreamed herself to make the Core Glyph and seal Agram. In the cartoon, the Core Glyph is formed from attaching the dreamstones to the Book of Elders. The makers of the cartoon were planning on a third season
There was a good deal of set up for it. Agram's ghost escaping to Earth through the Cald Obelix. Chur's promise of building his own army to take Agram down. Strag accepting his Core heritage. Warrador getting the limelight and a voice actor. Season 3 would have featured the Moonlands getting dragged into a 3 way war between different factions of Shadow Magi
We've got Chur making a push for taking Agram's throne. Warrador getting the limelight just screams of her getting promoted to more prominent villain status. More than likely she'll gather her own forces not unlike her card counter part and do some conquering of her own. And Agram's heads to Earth, who knows maybe he'd do some corrupting while he's away? Season 3 would have featured some of Strag's fellow Shadowstalkers
Really, no mention of them in the first 2 seasons at all. But with all the potential Shadow vs Shadow stuff that was hinted at, what better time would there be to reveal them. Yaki is the founder of the Shadowstalkers in the Cartoon canon
Really, who else would they use? Edyn would have gotten temporarily turned into a Shadow Magi in season 3
Strag and Tony both got their turns, Edyn needs hers. Chur is a Final Dreamer
At the end of season 1, the Book floats to Chur’s hiding spot in the wreckage of Agram’s castle in the middle of the ocean. He picks it up and it glows. The only other time it glows like this is in episode 1 when Tony first touched the Book, indicating that yeah he’s the Chosen One. Then Edyn and Strag touch the Book at the same time Tony does and it glows even brighter indicating that they’re the Chosen Ones.The Final Dreamer prophesy is mostly just about “the magi who’ll stop Agram once and for all and usher in a new era of peace to the Moonlands”.It makes sense that Chur is a Final Dreamer in light of the events in Allegiance Lost. In that episode a purified Chur teams up with the Dreamers to save Tony’s grandpa. In the process they travel around the Moonlands allowing Chur to learn about the other cultures of the moon in a peaceful context, make strong friendships, and show people that shadow magi can change and be good people. At the end of the episode Chur sacrifices himself to save Tony and becomes a shadow magi again. However this time he has a lot more power and does not feel like serving Agram. Actually he tells Agram that he’s going to raise and army and come back to finish what got started here.Revolting against Agram’s leadership of the Core and possibly taking it over himself would go along way into defeating Agram and ushering in a new era of peace.