Today kicks off the "Week of Metal" for Magic: The Gathering's main news hub, DailyMTG, and with it we have news of two new Planeswalker characters appearing in Kaldheim: Niko Aris and Tyvar Kell. Two articles were published on DailyMTG that each delved into one of these new characters, including their identities in the world of the game and their planeswalker powers.
Tyvar Kell, the first of these two characters, is a Wood elf native to Kaldheim. He is the brother of Harald, king and unifier of the Wood elves and the Shadow elves. Tyvar is framed as an overconfident braggart, who is nonetheless generous and good-natured. He is determined to be known for heroic deeds throughout the plane. According to the article on his character's story development, Tyvar does not live in the shadow of King Harald, like so many other cases (think Claudius in Shakespeare's Hamlet, or Scar in The Lion King), but instead seems to thrive on his status.
Tyvar's powers as a Planeswalker include the ability to reshape natural materials into new forms. According to Gerritt Turner, the Senior Narrative Designer for Magic: The Gathering:
This makes him especially aware of the natural world around him, and he has a special knack for using the environment to his advantage. He might cover himself in stony armor for protection, sprout thorns to escape a grapple, or even coat himself in molten lava[...]
These buffs are not limited to his own use. According to the article, Tyvar is able to share his boons with allies as well. It's hard to tell how these abilities in particular will translate to the table, but a hexproof-granting ability isn't likely off the table.
Tyvar is a character "locked in a wrestling match with his own ego". This seems to slot him in as a black-aligned character, albeit one often conflicted by this fact. His saving grace is his generosity. As a Wood elf character, Tyvar may also be green-aligned.
Niko Aris, another Planeswalker in the Kaldheim set, is from Theros. Because Theros is a plane of existence that contains a lot of subtext revolving around fate and destiny, Niko makes sense as a character who is not content with simply letting things happen to them.
It's important to note that Niko is a nonbinary character, and the writers use "they/them" pronouns to refer to them. However, this is not meant to be the defining trait of the character. Niko is a trained athlete who wished to challenge their fate. They threw a competition and realized that their destiny was not immutable. This ignited their Planeswalker spark and eventually Niko found themself on Kaldheim. Niko's realization that their fate is theirs alone is an excellent metaphor for the nonbinary experience, but is also universally relatable to those without that lived experience as well.
Niko is a master javelineer, as that was their favored sport on Theros. This translates well into their magical capabilities—Niko is able to conjure mirrored shards, trap enemies or allies alike within them, and throw them far away. This ability may manifest as a controlling blink effect, but, seeing as the card has not been officially revealed yet, there's no telling here. Niko is decidedly blue-aligned, although we may also see red or white in their color identity considering how they are not satisfied letting things be, and the whole imprisonment in the shard of a mirror ability seems to translate just as well to a white alignment as it does to blue.
This isn't the entirety of Kaldheim's Planeswalker roster. In addition to Tyvar and Niko, we will see new planeswalker cards for both Kaya and Tibalt! Unfortunately, articles regarding their involvement in the storyline haven't been published (yet), but it seems likely that we'll know why they're in this set soon.