One of my favorite characteristics of Pioneer is how it gives previously used or ignored Standard cards a new lease of life. A recent example of this is Inverter of Truth. Even during the release of Oath of the Gatewatch, it saw no play due to its unique effect, and yet it's become one of the most prevalent creatures in Pioneer thanks to Thassa's Oracle. Even before the dominance of Inverter of Truth, we have seen other cards discover a newfound application in Pioneer, the key one being Possibility Storm.
If you are unfamiliar with Commander you may not have had much experience with Possibility Storm. However, it has created an interesting strategy in Pioneer since the format's inception. Originating from Japan, Gruul Possibility Storm is a combo strategy that uses the adventure mechanic to provide consistent hits off the enchantment. The game plan is simple: first, deploy a Possibility Storm, then cast a sorcery adventure spell, which will always hit Enter the Infinite if you have not drawn it.
As a result, you will resolve Enter the Infinite, drawing your whole deck and putting a card back on top of your library, which in this case will be Borborygmos Enraged. Then, you cast a zero-mana creature such as Walking Ballista, triggering Possibility Storm to put Borborygmos Enraged into play. Finally, you activate Borborygmos's ability multiple times, slinging the lands you've drawn at your opponent until they're dead.
Gruul Possibility Storm feels akin to Ad Nauseum in Modern, since you are digging for a particular card that lets you discard lands to win. However, unlike the Modern strategy, the Pioneer version offers other routes to victory if you cannot set up the combo. Let's begin by looking at Gruul Possibility Storm from a budget perspective and the various approaches the strategy offers.
Rounding up to roughly $105 (or 37 tix on Magic Online), this budget variant provides a decent starting point. As you can see, the strategy can take on a Gruul Midrange role that utilizes Possibility Storm fairly if required. By running a set of both Elvish Mystic and Llanowar Elves, you are comfortably able to deploy threats ahead of curve such as Legion Warboss, which can put other strategies behind. Later on, you can transform these mana dorks into powerful threats such as Glorybringer if you are feeling confident with Possibility Storm.
Gruul Possibility Storm utilizes the adventure mechanic best by using sorceries such as Heart's Desire (Lovestruck Beast) which can find Enter the Infinite with Possibility Storm in play. Even Stomp (Bonecrusher Giant) can find Shared Summons which allows you to find Lovestruck Beast to go off with Enter the Infinite.There are various nuances to this strategy which will take time to understand, especially knowing when to be the aggressor or to go for the combo. However, Gruul Possibility Storm is a unique and fun strategy which offers plenty of game against the top decks, especially if your opponents are not prepared for it.
Running planeswalkers may be an odd inclusion with Possibility Storm in the equation, but their application benefits both approaches within the strategy. Domri, Anarch of Bolas promotes damage if you choose to go aggressive, and can also offer an uncounterable clause on your creatures if you want to safely wheel with Possibility Storm. Kiora, Behemoth Beckoner rewards you for deploying powerful threats that provide more fuel for Possibility Storm. Remember to stack your triggers correctly if you have both Kiora and Borborygmos in play, as you could lose the game by being unable to draw any cards off Kiora's passive ability. It's common to sideboard out your Possibility Storm package game two if the matchup is unfavorable and adopt a Gruul Midrange or aggressive approach, which negates any of the enchantment hate your opponent may bring in. However, it's good to get into the habit of understanding what cards are left in your deck and evaluating the probability of hitting a certain card with Possibility Storm. On the surface, Possibility Storm is a chaos card, however, if used correctly you can mitigatesome of the variance in your favor.
There are a few factors to keep in mind when playing the strategy, such as how Possibility Storm operates against spell-dense strategies such as Boros Feather. Possibility Storm actually benefits Boros Feather, as keywords such as prowess and heroic have the potential of triggering twice. Boros Feather boasts a high density of instants which means they can cycle through them with Possibility Storm and grow their board swiftly. Although Possibility Storm shuts off Feather's replacement effect, it does trigger Tenth District Legionnaire even if the spell is exiled with Possibility Storm, which can trigger multiple scrys if the spells are targeted on the creature. Possibility Storm does warrant Judge calls due to its unique templating, however, it's a good idea to get the fundamentals down so you understand how your cards work.
As with many of the Pioneer builds, the number of upgrades are minimal but offer more consistency and power. The optimal list we are using is from Zeth4 on Magic Online, who regularly 5-0's with Gruul Possibility Storm in the Pioneer Leagues.
To begin, we are adding a playset of Stomping Grounds by removing two Game Trail, one Mountain and one Forest. Unfortunately, we are limited with our land selection due to Karplusan Forest and Copperline Gorge being illegal in Pioneer. However, I foresee this changing in the upcoming sets to balance out the color pairings in the format overall. This limitation is one of the core reasons Gruul Midrange (or Aggro for that matter) has not broken out to be a tier 1 strategy. Mana consistency is incredibly important since the omission of fetchlands.
Although the creature core is largely unchanged, we are adding a single Walking Ballista over the Stonecoil Serpent as it's the better zero-cost creature. Walking Ballista complements our sideboard options like Hornet Nest since we can convert those counters into flying deathtouch threats.
Thirdly, we are optimizing our planeswalkers by replacing Kiora, Behemoth Beckoner with Chandra, Torch of Defiance. Although Kiora offers plenty of versatility, Chandra brings inevitability and fits well within the secondary Gruul Midrange plan. Also, Chandra's ultimate doubles up if you have a Possibility Storm in play, which means you can chain off spells instead of going for the Enter the Infinite combo. Overall, Chandra, Torch of Defiance is a resilient planeswalker that offers plenty of flexibility no matter which game plan you choose to adopt. Rounding out the upgrades we have Scavenging Ooze in the sideboard replacing Dryad Militant. Scavenging Ooze rewards graveyard maintenance with power and is a staple in green-based Pioneer strategies at present.
When we see powerful cards make an impression in Standard, they follow the trend of transferring favorably over into Eternal formats. However, we rarely look at the other end of the spectrum of what cards didn't work in Standard and whether they can be repurposed for Eternal application. Possibility Storm was one of the first cards to break this trend, which created a new philosophy in Pioneer: a philosophy not built on softer Modern strategies or previously successful Standard strategies, but on creativity and innovation. I'm excited to see which previously ignored Standard cards will impact Pioneer going forward, as I think Inverter of Truth and Possibility Storm are the start of something great within the format. You could say, the possibilities are endless.