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For as long as Mox Opal has existed, there have been those who sought to claim its power for their own. These evil souls use many nefarious means to do so. First, they Ravaged, then they Stirred, before finally Whirring past the competition. Today’s era has adapted to this nefarious presence, but powerful artifacts are not likely to leave this world. From unique play patterns to an exceptional ability to play your entire hand on Turn 1, decks with Mox Opal create a diverse experience for those journeying through the Modern format — while firmly able to be attacked.

In this article, I’ll be discussing card choices for a powerful new Mox Opal deck — Grixis Urza (or Grixis Whir in some circles). I’ll be highlighting both combo and support pieces, as well as offering recommendations on numbers in both the main deck and the sideboard. Each piece plays an important role in the machine that is Thopter Foundry, and check it out for all the devious tools available.

The Combo

Urza, High Artificer | A Modern Horizons standout earning hype for its presence in Commander, Urza serves two roles in Modern. First, as an enabler for Thopter Foundry and Sword of the Meek. By tapping either the Thopter or the the Sword, Urza can generate infinite mana and infinite life. This then lets you cast your entire deck with Urza’s activated ability. The second role of Urza is as a powerful threat — with a suite of artifacts, it’s not unusual for Urza to represent five or more power for four mana.

Thopter Foundry | One of the combo pieces for this prison style deck, Thopter Foundry combines with Sword of the Meek to turn one mana into a Thopter and a life. Additionally, Thopter Foundry can convert Nihil Spellbomb and Ichor Wellspring into both a card and a Thopter, giving the deck a reasonable back up plan.

Sword of the Meek | The other combo piece with Thopter Foundry, Sword of the Meek sets up the combo in one of two ways. If it’s in your graveyard, any sacrificed artifact to Thopter Foundry will return it to play, allowing you to sacrifice it again. When Sword of the Meek is in play, it can be used to start this process. Additionally, Sword of the Meek makes the most recently generated artifact into a 2/3 — a far more reasonable clock.

Goblin Engineer | A card I’ve been pretty excited about, which you can see in our Boros Refurbish brew, Goblin Engineer gives Thopter Sword combo an additional level of consistency. It also gives a value engine for Ichor Wellspring and Nihil Spellbomb — by looping these cards with Engineer, you can draw an extra card each turn, though the fragile body and Red mana requirement make Goblin Engineer less than a four of, but Arcum’s Astrolabe helps generate Red mana.

Whir of Invention | A staple in many different artifact shells, like Whir Prison, Whir of Invention functions similarly to Chord of Calling in older Devoted Druid builds. It can find prison cards like Ensnaring Bridge or Pithing Needle, but also serves as a way to find the missing combo pieces. While unable to find Urza, setting up the Thopter Sword value engine in the mid game is an excellent way to buy time for the combo kill.

Engine Pieces

Sai, Master Thopterist | A former KCI icon, Sai gives Grixis Urza an extra aggressive plan while doubling as a card advantage engine. With Sword of the Meek, Ichor Wellspring and Nihil Spellbomb as excellent artifacts to sacrifice, Sai can turn into a true card advantage engine. Sai also gives an avenue of attack through Collector Ouphe and Chalice, as spells that get countered still generate thopters.

Mishra’s Bauble | An early artifact to help cast Whir of Invention that cantrips, Mishra’s Bauble is a standard issue trinket. While the information is relevant, Bauble’s primary purpose is as an early game play that even supports Ensnaring Bridge.

Arcum’s Astrolabe | Like Mishra’s Bauble, Arcum’s Astrolabe serves an important role in Grixis Urza. While not a free spell, Astrolabe gives the deck smooth mana in the early turns, while ensuring enough artifacts to cast Whir of Invention. It also draws a card immediately, letting you chain multiple copies or use the permanent for Sai or Engineer. While Astrolabe requires mana concessions, a Fetchland and Basic heavy mana base is suitable for an artifact heavy deck.

Nihil Spellbomb | Mostly earning its spot due to the former Hogaak menace, Nihil Spellbomb fills the need for a critical mass of cheap, cantripping artifacts while filling the graveyard hate slot that all Whir decks play. Two copies is sufficient, though one could be cut for a variety of options.

Pyrite Spellbomb | While not quite the haymaker silver bullet of Nihil Spellbomb, Pyrite Spellbomb nonetheless serves as an important piece of interaction. By removing an early threat or looping with Goblin Engineer, Pyrite Spellbomb gives Grixis Urza an extra cantrip in the early game that slows down opposing aggro decks. With the recent demise of Hogvine in its current form, it may be worth revisiting a distribution of Pyrite Spellbombs. If the graveyard matters less, more removal may be a good call.

Ichor Wellspring | Two mana plays are significantly worse with Whir of Invention, but the ability to loop with Goblin Engineer makes Ichor Wellspring a good card to run, at least in some capacity. Most versions play two copies right now, though less or more depends on the specific metagame — if the format is filled with Humans and Infect, cutting Wellspring for removal is likely the route to take.

Support Cards

Pithing Needle | Having an answer to Karn, the Great Creator and other planeswalkers shores up one of the weaknesses of Ensnaring Bridge. Pithing Needle can also shut down problematic permanents like Oblivion Stone or Inkmoth Nexus, while doubling as an artifact for Whir of Invention.

Mox Opal | A longstanding Modern menace, Mox Opal enables some of the most broken starts in the format, and warps deckbuilding to include a swath of cheap artifacts. A Turn 1 Mox Opal enables crazy fast Turn 3 kills, while dumping your hand to turn on Ensnaring Bridge. Four copies is an absolute must.

Ensnaring Bridge | Another silver bullet available to Grixis Urza, Ensnaring Bridge gives the deck access to a “board wipe” of sorts. Like Mono Red Prison in other formats, Ensnaring Bridge is often one sided — with a bevy of low cost artifacts and a horde of 1/1 flyers, it is quite common for the deck to kill through an Ensnaring Bridge. One copy is adequate due to Whir of Invention.

Spine of Ish Sah | An unorthodox addition to Urza decks, Spine of Ish Sah gives the deck a combo kill of sorts — in addition to infinite life and Thopters, the infinite mana generated can be used to loop Spine of Ish Sah to destroy every permanent on the opponent’s side of the field. This should be enough to generate a kill with an Urza token or a host of flyers.

Blast Zone | While not an artifact, Blast Zone is still an integral part of most colorless decks. It gives the deck access to an uncounterable sweeper that can handle a variety of permanents — like planeswalkers or Stony Silence. Perhaps the most effective use is against Humans, where most of the threats in the matchup cost two mana.

The Sideboard

Ceremonious Rejection | With Tron and Chalice decks growing in popularity, Ceremonious Rejection serves as the primary stopgap for those strategies. While it does little to stop the big mana engines, it shuts off perhaps the most important colorless card against Grixis Urza — Karn, the Great Creator.

Lightning Bolt | Humans is an exceptionally disruptive deck that can often win the game through an Ensnaring Bridge, and can use Meddling Mage and Kitesail Freebooter to prevent us from even getting off the ground. Lightning Bolt slows them down enough for us to resolve our more impactful threats, and can free up spells from underneath a Kitesail.

Dead of Winter | While less effective than Anger of the Gods against most decks, Dead of Winter earns its spot mostly due to the scalability of it — you can even kill larger threats like Reality Smasher. One copy is sufficient, though I would consider an additional copy or an Engineered Explosives if Humans is more popular.

Ghirapur Aether Grid | Another sideboard option for Humans, Ghirapur Aether Grid also gives Grixis Urza a way to pressure Karn and Collector Ouphe, as it bypasses the Stony Silence effect. One copy is adequate, though you could play a second.

Mirrodin Beseiged | A fringe option, Mirrodin Beseiged serves as additional copies of Sai or an alternate win condition in grindier matchups. Definitely a better option in a Hogaak-light metagame.

Leyline of the Void | The graveyard still matters in Modern, and Leyline of the Void is both castable and punishing. I would recommend fewer copies going forward, but three is still a satisfactory amount.

Tezzeret, Agent of Bolas | A constant player in Whir Prison sideboard, Tezzeret gives Mox Opal decks a quick clock that is immune to Karn and Collector Ouphe. He also pressures opposing planeswalkers, shoring up a weakness of Ensnaring Bridge.

Magmatic Sinkhole | While not an expected portion of the sideboard, Magmatic Sinkhole is a flexible answer that hits both Planeswalkers and most threats out of Humans.  One copy is adequate, though this is the most flexible slot in the deck. Consider using this spot to answer whichever decks you struggle against, though it is important to diversify answers.


Thanks for checking out our Grixis Urza Deck Tech. Check out our Modern page for updates on which decks we’re showcasing next.