I guess even Wizards is getting tired of constant spoilers. At least, that would validate Innistrad: Crimson Vow's really short reveal. Spoilers began on October 28 and were finished a week later. Not that I'm complaining. It means that I get to do this article with a full look at the spoiler for once. It also means that we got done with this fairly uninspiring set that much faster, and move on to other things. A win all around.
So, yeah, Crimson Vow doesn't have much for Modern. Not that it's unexpected given how Midnight Hunt went, but still. Modern got a lot of sideboard cards and three well-played cards from that one, at least. I'm not sure that anything from Vow will have much staying power in Modern. There are plenty of cards for which I can (and will in a few paragraphs) construct scenarios where they could be played. Some of these possibilities are solid engine cards and those are always worth keeping in mind whenever new cards are printed. You never know when an engine will be busted.
I should specify: these are all card advantage engines. Urza, Lord High Artificer and Devoted Druid/Vizier of Remedies remain the only true mana engines in Modern. Wizards has learned, and we're unlikely to see anything like Krark-Clan Ironworks again. There are plenty of ways to draw lots of cards in Modern as it is, but in the right deck and/or under the right circumstances, these cards could enable some utterly degenerate streams of cards or permanents to just swamp an opponent. Or, more likely, they'll forever remain "cards with potential" whose value is just too much work to tease out.
Eruth, Tormented Prophet
The first one is easily the most straightforward. Eruth, Tormented Prophet turns every draw into Harnfel, Horn of Bounty. Which is already a Modern-legal card, but Eruth costs less mana, and that does make a huge difference. Whether that's made up for by Eruth being a more vulnerable creature is hard to say. The bigger benefit to Eruth is that there's no need to get the ball rolling with a card to discard; every draw exiles two cards. Harnfel is an integral piece of Legacy Mono-Red Storm, and being cheaper and easier to get going could make Eruth work in Modern.
The question: why bother? Eruth's card advantage doesn't actually put cards into your hand for later. It's use it or lose it, and that really limits her home to combo. Storm isn't really viable anymore and even if it was, why would it bother with Eruth over Expressive Iteration? In fact, why would any deck bother with Eruth over Iteration? And that's ultimately the problem. Eruth has the potential to just snowball out of control in a single turn, but what is she building towards and how is that better than existing options? She feels like a card that could eventually find a home that doesn't yet exist.
Headless Rider is meant to be to Zombies what Xathrid Necromancer was to Humans. The problem is that the Rider is even less necessary in Zombies than Necromancer has been for Humans for years. Gravecrawler, Geralf's Messenger, Relentless Dead, Diregraf Colossus, the list goes on of Zombies that let Zombies shrug off mass removal. Rider does nothing new and isn't needed.
Still, Rider does have combo applications. Zombies often includes sacrifice combos, and Rider doubles the fodder for said triggers. Why Zombies needs to double its fodder isn't clear, but this could push the deck in a more directly combo direction. Which might help the deck actually see play because it has never had much traction in Modern. No matter how good the beaters have been, without disruption, it just can't keep up. Perhaps going more for sacrifice combos is what is needed and if so then Rider is a perfect Zombies card.
Wizards clearly intended for this Drake to be enchanted. However, it has flying instead of hexproof, so there's no chance of it being a big Bogles payoff. Kor Spiritdancer is better in that context. However, the potential for this card to draw your entire deck certainly exists. The problem is that it won't be easy. Given the name, the obvious pairing to make Stormchaser Drake absurd would be the storm mechanic. The problem is that there aren't many of those and only ones that target creatures are Grapeshot and Ground Rift. However, Wizards clearly thought of that, and since Drake has flying, Rift isn't an option. Which just leaves Grapeshot, and why would you target your own creature and not the opponent with that card? The same goes for replicate spells.
There is the option to just target Drake with lots of spells like Kiln Fiend-style decks. Chaining Mutagenic Growth and other pump spells could produce a self-sustaining chain that ends in a single lethal swing. However, Drake dies to a stiff wind and Modern is filled with removal, far more than in Kiln Fiend's... I guess it was a heyday? More importantly, how is targeting Drake better than the alternatives? Such a deck would be somewhere between Prowess and Infect, neither of which are doing well right now. Additionally, Drake is far more of a glass cannon than either of those decks. So I don't see it. That said, there is so much (potential) value to be wrung from that I wouldn't be surprised if I overlooked something. Or if a Ground Rift-esque new card comes along and busts Drake.
Torens, Fist of the Angels
Just like with Headless Rider, Torens, Fist of the Angels has the potential to create utterly absurd boards. Unlike the Rider, Torens is a value play. Humans has been playing Adeline, Resplendent Cathar, and Torens can make far more tokens in a turn. However, I really don't think that such a fair use is Torens' destiny. Rather, Torens combos with Memnite and Ornithopter to just flood the board with dorks. I'm not sure how such a turn would be set up, but it wouldn't be unheard of for some Cheeri0s-style combo deck to utilize this engine.
But then what? I genuinely don't have anything beyond "Torens and 0-mana creatures makes huge board." It would generate a big storm count quickly, but how does that win the game? How do you keep the flow of dorks up? Or even get it going? And if you're not trying to win via Grapeshot, how does this win? Combo players: there may be something here. Have at it!
There are also a staggering number of cards that provide cantrips or better with the stats to potentially make it in Modern. The problem is either that there isn't a deck which they fit into or the metagame isn't right for how the card wants to be used. Whether or not the right metagame is plausible is another matter, but all of these cards definitely could make it in the right home.
Vow has a cycle of cards that exile a graveyard card on entering the battlefield and then get some value from the card type. And for the most part they're mediocre at best. Yes, even Cemetery Gatekeeper. It's no Eidolon of the Great Revel; it's just too easy to play around. Remember how Harsh Mentor worked out?
Cemetery Illuminator is the only one that could see extensive play. The reason is simple: Illuminator allows its controller up to two extra spells per turn cycle. Actually having it work out to exile the right card and then have two to play off the top of your library consistently is unlikely without a lot of setup, especially since nothing like Sensei's Diving Top is legal. But there's a chance for a lot of value.
Given the creature type, the first thought for making it work is Spirits, but that's unlikely to happen. Spirits doesn't have room at three mana as it stands. It will also be hard to set Illuminator up, though Vialing in Illuminator definitely reduces mana pressure. More likely I think some kind of midrange deck looking to exile instants wants Illuminator. That way they're guaranteed to be able to play the cards on the opponent's turn. The catch is that there isn't a deck that wants it and again, there aren't many efficient ways to set it up in Modern. If one does exist though...it's still a vulnerable creature. Maybe in Vintage?
I'm staggered by the potential here, yet confounded by the actual utility. Wandering Mind is a very powerful Izzet effect at a reasonable price given the body. Anticipate and Peer Through Depths have seen Modern play before, and Mind digs much deeper. Being sorcery speed isn't really a problem given Izzet being quite proactive and the dig being a great way to set up a continuing value chain. Any Izzet deck looking for a dig spell would be well served.
But, what deck might that be? The current crop of tempo and Prowess decks don't need Mind, nor does it fit into their usual threat categories. It's too costly and doesn't grow, though flying is welcome. Also, those decks don't need to dig deep since they're cantripping though their deck too quickly. Mind needs a slower style deck that needs to find specific answers or maybe combo pieces to shine. Such a deck does not exist, and even if it did I'm not sure that Mind is better than extra cantrips. It feels like a good card that will never have a home.
On a similar note, I really like Welcoming Vampire. It's a decent though not exceptional body that fits into white-based creature decks and fills a hole in many of them. Card draw has been getting increasingly easy to get and is necessary, after all. Thus, she's a very solid addition. But that's not enough. Despite being gracious to others, Welcoming Vampire doesn't do anything alone, and her stats aren't exceptional. The ability doesn't trigger on itself, only others, and that's a huge strike against playability. It also doesn't disrupt the opponent or have tribal synergy with anything. The deck that wants Welcoming Vampire is a grindy Wx Valuetown style deck, and that hasn't been viable in Modern in years. Thought it would be very strong in such a deck.
Good Cards for Bad Decks
And finally, there are a number of cards that are only potential additions for some mediocre to actually bad decks. These cards will be very good in said mediocre-at-best decks, but only realistically in those decks. Which probably means they won't see any real play, especially since none of these cards will fix what's wrong with their host decks. Thus, they're really just enthusiast-only cards.
So Many Zombies
Appropriately enough, there are a number of Modern-viable Zombies for the tribal deck beyond the more combo-oriented Headless Rider. The headliner for all these cards, both in terms of power and why they won't see play, is Graf Reaver. A 3/3 for two with a drawback isn't Modern playable, but a 3/3 for two with a drawback that's also removal is. And Reaver killing planeswalkers is extremely relevant right now. Trading a Gravecrawler for Wrenn and Six or Teferi, Time Raveler and leaving behind a better body is pretty good value.
The catch is that Zombies already has spells to kill 'walkers and can just attack them. What it needs is either tribal pump effects or disruptive creatures à la Humans. As it's not getting any of those, just more beef, its viability won't be changing. It had all the beef it needed already.
Any deck that untaps with Hullbreaker Horror, instants in hand, and a way to get more will win the game. Simply put, no relevant spell is going to resolve, and the board will soon be clear for good. Uncounterability doesn't impact this reality. The catch is that since Horror costs seven, it will be quite hard to meet those conditions the turn it comes down. Solitude being the most played removal for big creatures, Force of Negation is no help. UWx can do it, but why should they bother when what they're doing now is so successful?
Wilderness Reclamation decks, on the other hand, often hit the needed mana early and then have plenty to spend protecting Horror and riding it to victory. It would be quite trivial for such a deck to float the needed mana, untap on end step, and then cast and protect Horror. However, Reclamation is not a good Modern deck. When everything comes together, it's very powerful right now, but the problem is actually getting everything to come together. The whole deck is built around resolving a four-mana enchantment and keeping it in play until end step. That's not easy as-is, and Horror does nothing to help. So I don't see it working out.
Kaya, Geist Hunter
Years ago, WB Tokens saw play because it had a decent Jund matchup. The deck based on 1-for-1 trades unsurprisingly has trouble with cards like Lingering Souls which skew the math. However, as Modern has evolved, the weaknesses of Tokens have become too exploitable, and the grindy rock gameplan it targets has fallen from favor. Thus, it doesn't see much play, and isn't really part of the metagame anymore.
However, Kaya, Geist Hunter is a great card for that deck. The biggest problem for the deck is how dinky the creatures are, and being able to permanently pump them is pretty good. Additionally, the -2 ability is very strong when it's making 6+ Spirit tokens. Of course, the deck will still struggle for all the reasons it currently struggles, but at least when things are going well, they'll go much better.
It Can Still Work Out
And that's Crimson Vow. There are plenty of cards to try and brew around, but the power level is noticeably lower than even Midnight Hunt. That's not a bad thing, but it does meant that Modern is unlikely to change much for the foreseeable future. Whether that's a good thing or not depends on your perspective.