Nearly one year since the last change to the Modern banned list, R&D has continued to monitor the evolution and health of the format. During this time period, Krark-Clan Ironworks decks have risen to prominence at the Grand Prix level of play, posting more individual-play Modern Grand Prix Top 8 finishes than any other archetype, despite being only a modest portion of the field. In fact, only one other archetype, White-Blue Control, has posted more than half as many Top 8 finishes as Ironworks in those events. With no signs of the Ironworks deck's dominance at the GP level slowing down, we've decided to take action by banning the card Krark-Clan Ironworks.
In many ways, this was not a clear-cut discussion, and R&D considered data over an extended period of time before coming to a decision. Ironworks decks require detailed rules knowledge and careful practice to master, resulting in a high win rate among pro players and other experienced pilots at the highest levels of play. In contrast, for quite some time, we hadn't seen Ironworks be as popular or as winning in less competitive play environments. With Ironworks's interactions being difficult to execute on Magic Online, it's been more challenging to gather data reflective of its win rate in the hands of a practiced pilot in tabletop play.
With these challenges in mind, we've taken additional time to watch the environment evolve. By now, we've gathered sufficient data to conclude that Ironworks poses a long-term threat to the health of competitive Modern play. This is the right time to make a change. While the primary reasons for banning a card from the Ironworks deck are its raw win rate and high GP Top 8 conversion rate, we also considered its highly polarized Game 1 (pre-sideboard) win rate, sometimes long turn length, and difficult rules interactions as secondary factors.
Games with Krark-Clan Ironworks can often involve excessively arcane rules interactions using mana ability timing windows, the understanding of which are necessary for players to agree on the game state. This can create a barrier to entry to Modern for players playing against the deck and to those who would feel obligated to play with it because of its strong win rate. We're sensitive to community feedback that the combination of polarized matchups, complex interactions, and long turns can lead to unenjoyable gameplay and viewing experiences.
Make no mistake—R&D wholeheartedly embraces the strategic depth and robust rules system of Magic, and the player skill it takes to master them. In many cases, a deck's difficulty to play is a pressure against needing to ban a card, insofar as it suppresses the metagame population and win rate of the deck in the short term. This a major factor as to why R&D had not previously needed to take steps against Ironworks. As time goes on and more players master the deck, we ultimately have to make decisions based on how the deck is performing in the hands of those experts in practice.
I'd like to emphasize that, while Ironworks did perform well at the recent Grand Prix Oakland, we do not make B&R decisions based on a single tournament alone. It's the long-term performance of Ironworks over the last year that has given us cause for action. Grand Prix Oakland results reflect that this trend is not slowing down as the metagame adjusts.
We considered three possible cards from Ironworks to ban: Ancient Stirrings, Mox Opal, and Krark-Clan Ironworks itself. Given that Modern has looked healthy and diverse at many levels of play outside of Ironworks's dominance at the Grand Prix level, we decided to target the card that only affects the Ironworks deck: Krark-Clan Ironworks.
Ancient Stirrings and Mox Opal represent two categories of cards that R&D keeps a careful eye on: card selection and fast mana. One factor we consider is that Ancient Stirrings, unlike more general card selection spells like Ponder and Preordain, brings deckbuilding restrictions. When we examine the effect of powerful cards, we consider whether they are increasing or decreasing the number of viable decks in the environment. In the current state of the metagame, the build-around nature of Ancient Stirrings supports decks that look very different from a simple collection of the strongest rate cards, and that otherwise may not exist. The recent resurgence of a new generation of Amulet Titan decks is a good example of this. Mox Opal is a similar case. In addition to showing up in high-profile decks like Hardened Scales, we also see Mox Opal enabling a variety of more fringe artifact synergy decks. As a category, we think these are generally healthy provided they appear in small doses and have reasonable win rates. As Modern stands, our metagame data does not indicate a need to impact the other Ancient Stirrings or Mox Opal decks.
Bear in mind that this is based on the current state of the metagame, and that Ancient Stirrings and Mox Opal are not being given a free pass in perpetuity. While we have no current plans to take action against these two cards, we'll continue to monitor the health of the environment and the strength of decks that use them. If the metagame reaches a point where we determine these cards are doing more to suppress archetype diversity than enable it, we will certainly revisit this discussion. At this time, we're choosing the surgical ban against Krark-Clan Ironworks itself and avoiding "splash damage" against other archetypes.