Helvalla's Adorned is pretty impressive, as far as Fiend Hunters go; I think it'll see some play in D&T style decks. Angel of Promised Glory very notably doesn't specify that its target must have been put into that graveyard from the battlefield; while I don't anticipate that getting abused for reanimation, it's certainly an option, and regardless it's a decent midrange card. Valley Outcast is a strange tutor, probably not playable, but I wouldn't be that surprised. Heart of Odelia slots right into the classic W/B Lifegain deck. Harsh Unpreparedness is yet another Oblivion Ring; I think it's more playable than Judge's Decree, but weaker than Planar Eviction. Before the Storm is a Parallel Lives effect, but I think five mana's more than any current token deck wants to spend on it. Helvalla, God of Glory might be enough to make an Angel-tribal deck viable, relying mostly on Mious cards; it's certainly a decent commander for one, although not an ideal pick due to its mono-white nature. From what I've heard on the MSEM2 Discord, Fjorda's very playable in token lists, although it requires some adjustments to make every token get the buff. Alpine Almsbringer probably doesn't make the W/B lifegain deck, but it's worth swapping all the basic lands for snow lands and testing it. Giant's Wake is about as good as all our other five-mana boardwipes; better if there's a control deck using the new Snowstorm Titan or some other Giant as a finisher.
Young Abjumancer probably sees play in some version of UR Spells. Lorescale Serpent's a great top-end for a base-blue aggro deck. Irrblossom probably isn't good enough for UR Spells, but it might be worth testing in the U/X flying deck. Dawn of the Lights is the strangest planeswalker-hoser I've ever seen, but looks tragically unplayable. Echo Chamber looks like it could be a build-around for a very strange deck; I don't know what exactly that deck looks like. Chian MSEDH, maybe. Arcane Genesis, as a two-mana hard counterspell, might be playable; I'm not convinced. Ebilir, God of the Depths seems surprisingly mediocre. Snowswell Elemental might be playable in the right sort of hatebears deck. Snowstorm Titan looks like a good control finisher, especially in a WU deck that can also run Giant's Wake. If there's a snow-tribal deck, it runs Snowsculptor and Sphinx of Valhime Peak; if not, neither sees play. I love Think Ahead's flavortext, but I'd never run it over Opt. Fated Challenge is a great finisher, and probably completely broken — three mana's not nearly enough to pay for a cantripping Relentless Assault.
I wish this format had a way to break Necropresence. I don't see one, but I believe there's one out there. Uloff's Assertion is a mediocre sideboard option, but it's so vastly worse than Pithing Needle and similar effects (Tether of Simplicity, in MSEM2) I don't anticipate it ever seeing play. Maybe in MSEDH where you can just name their commander? Rising Snowbanks and Impending Doom are both good against token decks. Chill Through's okay removal that kills Declare, the Mother Bear and other indestructible threats. Nehel might be playable in a prison-style deck, but probably isn't. Essem's going to have a hard time finding places in decks; her -3's her only really exciting ability, given her cost, and Kalemn Weller fills a similar role for one mana cheaper. Still, she's a faster clock than Kalemn if your opponent has enough dead creatures. Snowstorm Legion probably isn't playable, even in W/B lifegain or the snow-matters deck, but I'm intrigued by it. Honorless Offering is one of mono-B control's best draw spells, if that deck's a thing. Promised Ascent is possibly the funniest anti-reanimator sideboard option in existence; unfortunately, it's bad against Eternity Witch and Liguno, and thus is unplayable in that role.
Saigura Brutalizer and Bergbreaker might be playable as finishers for Big Red decks, but I think there are better cards for that slot, like Sugon. Forsaken Mauler might see play in the Sligh decks that have been popular lately. Rallied Rabble might see play in the token decks. I really wish Avalanche was just a Skred reprint; as-is, it's unplayable, but a Skred would've been a huge push towards taking the Big Red decks NVA enables and pushing them up in tier. Stribius looks playable in any RG ramp deck looking to close games out with twenty damage of Fireball. Shaman of Pale Cold looks barely playable, maybe. Impulsive Plan is an incredibly strong draw spell for burn and aggro decks looking to turn excess land into midgame gas. Last Lash is also probably playable in the 20-in-one-go Stribius deck, or most mono-red aggro decks; side it out against control. It might even be playable in UR Spells.
Snowfield Mother looks like an all-star in anything midrangey. Laugar Lotus-Warrior might fit in a UG or RUG tempo deck — it's even a Warrior for PFP synergy. Peerless Brawler looks strong, I expect it to see play in aggressive green decks that aren't RG Infect. Frontier Hunter could be the top-end of a midrange deck with carefully chosen creatures. Snowsword Adept looks close to good but without some way to grant it evasion, it'll have a hard time being useful. Maybe UG Warriors wants it. Just kidding. Anyway, Promise of Spring is a passable finisher for ramp decks, vaguely resembling a Craterhoof Behemoth. Viridia the Forgotten One's a sideboard card to make control decks weep and never tap out again. I thank my lucky stars it can itself be countered. Rime Druid goes infinite with PFP's Exhaustive Toil, as mentioned in my PFP First Impressions article. Hardy Elk might be playable in Superfriends decks. Viridia's Presence makes combat math difficult to impossible, but isn't instant-speed enough to be any good outside of MSEDH.
Yngou the Snowbeast looks like a hilarious and fun ramp commander. Ravenwood Triad is very, very bad, because you start off by discarding three cards, then your opponent draws three cards, then they kill the Triad leaving you six cards behind. Amil the Seeker is probably too expensive to see play, but might be worth testing. Saigura Tam looks great in the Taiyohata Champion decks. Archangel of Hildrjorn is the sort of finisher control decks want. Note that you don't commit mana to the the card-draw trigger until after it's too late for countermagic, so you'll still have mana up to counter your opponent's counterspells. It will see play. Titan of Winter's Passing might, especially in Giant's Wake decks, but I wouldn't count on it.
Vantage Bridge is probably playable, especially in combination with topdeck manipulation; note that it triggers once for each attacker, but it checks the CMC of the top card only once, before you do any drawing. Put a high-CMC card on top, perhaps with PFP's Discordant Bell, and leave your opponent with a choice of not attacking at all or drawing you a card for every attacker. Gem of Ancient Treasures is fine in ramp decks for rushing a high-cost threat into play early — a manadork into the GoAT leaves you with seven mana on turn three, one short of a Liguno. Nothing else is especially exciting, with the possible exception of Sword of Eternal Frost in a Yakizma-heavy metagame.
Death of Yakizma's basics use the new Ixalan map template, which is cool; unfortunately, none of the art is particularly impressive, with the possible exception of the Swamp. For that matter, why does Death of Yakizma even have nonsnow basic lands? Couldn't we just have Snow basics with that template?
Speaking of Snow basics, yep, we've got those. I expect them to replace regular basics a lot of the time, given how much support and relatively little hate there is for them here.
There's also a cycle that's just the Temples from Theros block, except they're Snow (like Winterheath Pass). They'll see play only in decks that are taking Snow especially seriously, I think, and even then aggressive decks would probably rather just run basics and fetches.
Winterheath Snowbank, Winterheath Tundra, and Northern Holdout are an odd sort of miniature Urzatron. Northern Holdout is strangely not a snow land. I don't expect them to see play, largely because the payoff is relatively mediocre compared to the true Tron lands. Frozen Expanse, Frost Spires, and Encroaching Seasons are unlikely to be playable; Encroaching Seasons is the best snow-land-hate available, and it's still usually not worth hitting a basic snow land with it, so I don't see it stopping people from bringing snow basics even if it's a four-of in multiple popular decks for some reason.
White: Heart of Odelia
Blue: Fated Challenge
Black: Honorless Offering
Red: Impulsive Plan
Green: Viridia the Forgotten One
Multicolor: Saigura Tam
Artifact: Vantage Bridge
Land: Snow Basic Lands
Command Zone: Yngou the Snowbeast