The biggest Standard innovation to come out of Pro Tour 25th Anniversary was the Turbo Fog deck based around Nexus of Fate. The most successful version, which was tuned by legendary deck builders Gabriel Nassif and Mark Herberholz, was piloted by David Williams to a fifth-place finish.

# Turbo Fog

### David Williams, 5th place at Pro Tour 25th Anniversary

The dream is as follows:

**Turn 2**: Search for Azcanta.

**Turn 3**: Gift of Paradise.

**Turn 4**: Teferi, Hero of Dominaria. Draw a card, untap two lands, and cast Root Snare during your opponent’s combat step.

**Turn 5**: Draw a card with Teferi, tap two lands in your end step to float mana, untap them, and cast Nexus of Fate.

**Turn 6+**: In an ideal scenario, you keep repeatedly drawing and shuffling back Nexus of Fate to take every single turn from there on. Eventually, you can ultimate Teferi to leave your opponents without any permanents, and you can win the game with Karn’s Constructs.

If you want to see the deck in action, check out David Williams’ flawless victory in Round 8.

Lots of requests for the list and SB guide so here ya go. I think Ben Rubin and I went 22-6. Deck was absurd. Thanks to @gabnassif for the initial list and @herberheezy for the tightening up of the deck. #PT25 pic.twitter.com/3Zp1aIjG8v

— David Williams (@dwpoker) August 5, 2018

Given that the sideboard plan against Chainwhirler Aggro and Steel Leaf Stompy is described as “nothing” and “you’re good” respectively, Turbo Fog was probably the perfect answer to the Standard metagame at the Pro Tour. It makes sense: decks with big creatures can be beaten with a steady stream of Fogs, they don’t have the right interaction, and their creature removal is useless.

According to a tweet by Seth, probably better known as Saffron Olive, the Standard match win percentage of four of the six Turbo Fog players at the Pro Tour was 73%. With a corresponding sample size of 52 matches, the Clopper-Pearson method that I described last week allows me to say with 95% confidence that the true match win rate is between 59% to 84%. Even if you take into account that the pilots were among the most experienced players in the room, it’s very likely that this deck is extremely well-positioned in the current Standard metagame.

# The Card Availability Problems

Nexus of Fate can’t be found in booster packs. It is only available as the foil buy-a-box promo for *Core Set 2019*. This comes with two potential problems.

The first problem is limited supply. There wouldn’t be a problem if each booster box in circulation was associated with one Nexus of Fate—by comparison, an *M19* box contains 0.28 copies of any given mythic and 0.59 copies of any given rare in expectation—but you can only get the promo in WPN stores, and each store only gets a limited amount. Drafters or dealers can’t open packs to find Nexus of Fate. Unless Wizards decides to reprint the card, which is not as easy as increasing the drop rate in online Treasure Chests, all paper Nexuses are already out there.

So how big of an issue is this? Well, I haven’t found any numbers on the total supply of Nexus of Fate, so it’s difficult for me to estimate the impact. I can only get some indication by looking at the price in the secondary market. At the time of writing, Nexus of Fate’s paper price in the U.S. (which seems to be higher than in Europe) is similar to the price of Nicol Bolas, a sought-after mythic. I don’t have an issue per se with that price point. Although it’s arguably too much for a buy-a-box promo, it’s not an insurmountable barrier to entry for Standard. But there is a risk that an increase in demand, coupled with the constrained supply, could lead to a dangerous price spike in the future. There is no precedent for a card like this, and I understand the worries.

It is worth pointing out that a competitively-viable buy-a-box promo does accomplish the goal of promoting and rewarding local game stores that organize Magic events. To be fair, I don’t see why these goals couldn’t also be accomplished with a different promo, like a foil Sarkhan, but thriving local game stores are good for everyone.

Ultimately, to me as a tournament player, the most annoying problem with Nexus of Fate is that foils tend to warp. If your Nexus of Fates curl, then this can lead to playing with marked cards. Normally this wouldn’t be a big problem, as you could just replace them with a non-foil version instead. But Nexus of Fate doesn’t have one.

A similar issue came up with Kess, Dissident Mage in Legacy several months ago. Policies were changed to allow judges to make proxies for foil-only cards (as long as a player actually owns them) but in my experience, playing with proxies in tournaments is inelegant and confusing. Yam Wing Chun was holding such proxies on camera in Round 12 of the Pro Tour, and it just looks bad. I really wish there were a non-foil version of Nexus of Fate.

# And Now for Some Math: How Reliably Can You Go Infinite?

I couldn’t write an article about Nexus of Fate without addressing some of the controversy, but the actual reason I wanted to write about the card is because its shuffle clause yields an interesting mathematical problem.

Suppose that you have a 30-card library, 4 of which are Nexus of Fate. You are in your upkeep and draw two cards per turn, for instance via Teferi. Thanks to previous Nexus of Fates, you still have one extra turn stored in the queue.

From this starting point, what is the probability that you will go infinite by taking *all* the turns from here on out? And how do these numbers change if we vary the starting number of cards in our library, the number of cards we get to draw per turn, or the number of extra turns stored in the queue?

It’s a fun mathematical exercise, and we can solve it by modeling the situation as a Markov chain: a discrete stochastic process in which the probability of moving to a new state depends only on the previously attained state. For a given number of card drawing planeswalkers, the state space is the combination of your library size in your upkeep and the number of extra turns stored in the queue, plus two additional absorbing states: one in which your opponent takes a turn (utter failure!) and one in which you are guaranteed to take all the turns.

To set up the transition probabilities from one upkeep to the next, I will assume that we draw cards one-by-one and play any Nexus of Fate immediately. I also assume that you’re never constrained on mana to cast them and that all library cards other than Nexus of Fate are irrelevant. Since the transition matrix is sparse, I can describe how to generate the non-zero transition probabilities. To illustrate this, suppose we control one Teferi and thus draw two cards per turn. If the current state in our upkeep is described by a 30-card library and 0 extra turn markers, then:

- The probability of moving to the absorbing state in which our opponent gets to take a turn is (26/30)*(25/29). This corresponds to drawing a non-Nexus in our draw step and a non-Nexus with Teferi.
- The probability of moving to the state with an 29-card library and 0 extra turn markers is (4/30)*(26/30)+(26/30)*(4/29). The first element of this summation corresponds to drawing a Nexus in our draw step, casting and shuffling it back into the library, and then drawing a non-Nexus with Teferi. The second element corresponds to drawing a non-Nexus in our draw step and a Nexus with Teferi.
- The probability of moving to the state with an 30-card library and 1 extra turn marker is (4/30)*(4/30). This corresponds to drawing a Nexus in our draw step, casting and shuffling it back into the library, and then drawing a Nexus with Teferi.

All other transition probabilities can be generated analogously, except for the transition to the absorbing “we go infinite” state. We go there once we start the turn with a four-card library containing four Nexus of Fate. We are guaranteed to reach that state once our library size is smaller than the number of stored extra turns multiplied by the number of cards we draw per turn.

With this model, the probability of going infinite without ever giving our opponent a single turn can be straightforwardly determined from any starting state. We don’t even need to resort to simulation. My calculations produce the following results.

So if you start with 20 cards in your library, have 1 extra turn in the queue (which is similar to starting with a Nexus of Fate in hand), and draw three cards per turn (which is a conservative approximation of what happens if you control Teferi and Karn, or Teferi and Search for Azcanta) then in my model you’re already 50% to go infinite, i.e., to take all the turns without your opponent ever getting another.

Note that this is effectively a lower bound. After all, to facilitate exact analysis, my model assumes that every non-Nexus card in the deck is a blank. In reality, you may draw Chart a Course, Karn’s Temporal Sundering, more planeswalkers, and so on. A Root Snare would also be just as good as a Time Walk most of the time, and you’d probably transform Search of Azcanta at some point for additional card selection.

But despite the simplifying assumptions, I found it interesting to see how the probability of going infinite shoots up once your library hits 25 cards or less, which to me is a confirmation that the strategy is pretty reliable.

# How to Adapt?

Turbo Fog proved to be a viable deck with a high win rate at the Pro Tour. I expect that plenty of players will try to acquire Nexus of Fate to play the deck at Grand Prix Brussels or Grand Prix Orlando this weekend. But their win rate won’t be as high as at the Pro Tour because the competition will adapt.

The prominence of Fogs may drive red players towards more burn-heavy versions with The Flame of Keld. After all, a Root Snare doesn’t stop a Wizard’s Lightning to the face. Red players can also use Insult // Injury to stop Fogs from preventing combat damage. Meanwhile, Steel Leaf Stompy players may be incentivized to splash Fling, Sarkhan’s Unsealing, or Negate to get around the Fog effects.

Black players could adapt by adding Lost Legacy to their sideboards. And combo aficionados may opt for Mono-Blue Storm—according to David Williams, it was one of the hardest matchups.

There seem to be plenty of options to fight back. How are you planning to beat Turbo Fog?