Keen Engineering precon upgrade guide

Forty-three artifact spells means a lot of Thopters, and in this box only Sai can sacrifice them.

Sai, Master Thopterist makes a 1/1 flying Thopter whenever you cast an artifact spell, and forty-three of the box's 99 cards are artifact spells. So the Thopters come. What the box doesn't give you is much to do with them once they're out: they can attack, they can be tapped for Shimmer Dragon or Whirler Rogue, and the only card in the deck that can sacrifice one is Sai himself.

Sai is the only card in the box that sacrifices a Thopter

Sai's second ability costs {1}{U} and two artifacts for one card. That's the deck's whole conversion of Thopters into anything other than combat. Every other sacrifice in the box's 99 says "sacrifice this artifact" (Aether Spellbomb, Mind Stone, Hedron Archive, Soul-Guide Lantern) or "sacrifice this land" (Buried Ruin, Foundry of the Consuls), and All Is Dust only takes coloured permanents, which a Thopter isn't.

The box does reward a wide board of them. Master of Etherium and Chief of the Foundry give other artifact creatures +1/+1, Steel Overseer puts a counter on each of them, Forsaken Monument gives colorless creatures +2/+2, and Kappa Cannoneer grows and can't be blocked that turn whenever another artifact enters, which a Thopter token does. Research Thief and Thopter Spy Network draw when artifact creatures connect. That's a fine air force, and it's one plan. The upgrades below give the same tokens a second job, so a hand full of cheap artifacts turns into mana and cards as well as flyers.

What are the best Keen Engineering upgrades?

Ranked by how much more each one gets out of a Thopter. Prices are October 2026 market prices for the default printing.

1. Efficient Construction ($0.50). The same trigger as Sai, on an enchantment: whenever you cast an artifact spell, make a 1/1 flying Thopter. With both out, every artifact spell is two Thopters.
2. Ashnod's Altar ($16.74). Sacrifice a creature for {C}{C}. One Thopter from Sai refunds a two-mana colorless artifact, and with Efficient Construction out, a two-mana artifact nets you two mana. It also pays the {1} in Sai's draw.
3. Urza, Lord High Artificer ($16.31). Tap an untapped artifact for {U}, and that includes a Thopter that came in this turn. Tap two Thopters for {U}{U}, spend it on Sai's draw, then sacrifice those same two tapped Thopters to pay the rest of the cost. With Urza out, two Thopters are a card for no mana at all. He also brings a Construct that's +1/+1 for each artifact you control.
4. Retrofitter Foundry ($1.23). One mana, so it's a Thopter the turn you cast it, and then it taps and sacrifices a Thopter to make a 4/4 Construct. That's every Sai token upgraded into a real body, once a turn, or more often for {3} an untap.
5. Tezzeret, Artifice Master ($5.13). Starts on 5 loyalty, makes a Thopter with his +1 and draws two with his 0 as long as you control three artifacts, which this deck almost always does.
6. Ornithopter ($0.30). An artifact spell for zero. Sai doesn't care what it costs, so it's a free Thopter, and two with Efficient Construction out.

The other three adds are removal, and they're argued in the cut list beside what they replace.

All Is Dust stays, and Nevinyrral's Disk goes

The box has two ways to clear the board, and they treat this deck very differently. Nevinyrral's Disk destroys every artifact, creature and enchantment, and it enters tapped, so it gives a turn of warning before it does. On your side the only artifacts and creatures that survive it are the two indestructible ones, Darksteel Juggernaut and Darksteel Citadel. Sai, Propaganda, Thopter Spy Network and every Thopter go with the rest. That's a reset button for a deck that's losing, and this deck is usually the one with the most to lose.

All Is Dust costs seven and makes each player sacrifice everything that has a colour. In the upgraded 99 there are fifty-two nonland permanents, and thirty-three of them are colorless, so they stay. So does every token the deck makes: Thopters, Myr, Servos and Constructs are all colorless. What you lose is Sai, the blue artifact creatures (Master of Etherium, Kappa Cannoneer, Thought Monitor, Memory Guardian and the rest), and three of the adds above, Efficient Construction, Urza and Tezzeret. Your opponents lose every coloured permanent they control. It's a sacrifice, so indestructible and hexproof don't save anything, and Sai can go back to the command zone and cost two more next time.

Seven spells and two Islands, and the removal that fills the gap

Leaving out counterspells and bounce, the box has three cards that can target a creature and get rid of it: Skysovereign, Consul Flagship (3 damage when it enters or attacks) at five mana, Duplicant at six and Meteor Golem at seven. Three of the cuts become cheap answers.

Fall from Favor taps one creature and makes you the monarch, and it's an Aura, so it makes no Thopter. Rapid Hybridization takes its slot at {U}. It destroys a creature and its controller gets a 3/3 Frog Lizard, which is a fine trade against a commander. Mazemind Tome is the slowest draw in a deck that draws a lot: {2} and a tap per card, and it exiles itself after four page counters. Reality Shift replaces it, exiling a creature at instant speed for two and leaving its controller a face-down 2/2. Adaptive Omnitool pumps one creature and costs {3} to move. Brittle Effigy costs one, so it's a Thopter on the way in, and later {4} and a tap exile it and a creature with it.

Misleading Signpost is three mana for one {U}, and its redirect trick only works if you flash it in during the declare attackers step. Ashnod's Altar goes in at the same cost. Pull from Tomorrow is a fine instant, but it's {X}{U}{U} of draw that never makes a Thopter, and Tezzeret draws two a turn from the same slot. Nettlecyst comes with a black Germ token, which is the one token in the deck All Is Dust takes, and it's another single-creature pump. Efficient Construction replaces it.

Last, two Islands. The box runs forty lands with ten ramp cards and an average mana value of 3.8, and the swaps bring that to thirty-eight lands at 3.7, while the ramp count goes from ten to eleven. Ornithopter and Retrofitter Foundry take the slots. Spire Golem's affinity counts Islands, and with thirty-two basic Islands left it's still free once you have six of them out.

Graaz makes every Thopter a 5/3, and makes Sai attack

Graaz, Unstoppable Juggernaut gives every other creature you control a base power and toughness of 5/3 and makes them all Juggernauts, which have to attack each combat if able. On your Thopters that's a flying army of 5/3s, before Master of Etherium, Chief of the Foundry and Forsaken Monument add their bonuses on top. With all three out a Thopter is a 9/7.

Two catches. Broodstar and Master of Etherium set their own size by counting artifacts, and Graaz's 5/3 overrides that, so with more than five artifacts out he makes them smaller. And Sai, Urza, Padeem and Vedalken Archmage become 5/3 Juggernauts too, which means each of them attacks every combat it's untapped and able to. Tap them before combat to keep them home. Crewing Skysovereign, Thopter Fabricator or Cultivator's Caravan does it, and as a 5/3 any one of them can crew any of the three.

Duplicant, Myr Battlesphere and Forsaken Monument earn their mana

All three cost five or more and none of them looks like it does much the turn it lands. They stay.

Duplicant is six mana, and it exiles any nontoken creature, which makes it one of only six targeted answers the upgraded deck has. Myr Battlesphere brings four 1/1 Myr tokens with it, and those are four artifacts, which is two of Sai's draws if the board needs cashing in. Forsaken Monument turns every Thopter into a 3/3 and every other colorless creature bigger, and there are nineteen colorless creature cards in the upgraded 99. It adds one extra {C} whenever you tap a permanent for colorless mana, so Sol Ring makes three, not four.

Six artifacts at one mana or less, where the box had three

Sai rewards casting artifacts, not owning them, so the count that matters is how many you can cast in a turn. The box's artifact spells at one mana or less were Sol Ring, Aether Spellbomb and Soul-Guide Lantern. The swaps add Ornithopter, Retrofitter Foundry and Brittle Effigy. Artifact spells overall go from forty-three to forty-two, because five of the cuts were artifacts and four of the adds are.

Cards that sacrifice a Thopter go from one to three, Sai plus the Altar and the Foundry. Targeted creature removal goes from three cards to six. Eight cards now ask for {U}{U}, including Urza and Tezzeret, and thirty-nine blue sources give you two of them by turn three 93% of the time on the play. The bracket floor stays at 1, and none of the nine adds is a Game Changer.

Two cards I left out. Unwinding Clock ($22.43) untaps all your artifacts during every other player's untap step, so Urza, Shimmer Dragon and Whirler Rogue get to use the same Thopters again on each opponent's turn. It's the next thing to buy once the list above is done. Cyclonic Rift ($39.16) is the usual blue sweeper for a deck like this, but it's a Game Changer and would lift the deck's bracket, and All Is Dust already does the job here.

The upgraded decklist

Sai and the 99 with the nine swaps made, sorted by card type. Hover a name to see the card and its price.

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FAQ

Does Sai still make a Thopter if my artifact spell is countered?

Yes. Sai's ability triggers when you cast the spell and resolves before it, so the Thopter is already on the battlefield by the time a counterspell could matter. Efficient Construction works the same way, so with both out a countered artifact still leaves you two Thopters.

How much does it cost to upgrade Keen Engineering?

$41.69 for all nine adds at October 2026 market prices for default printings. Ashnod's Altar and Urza, Lord High Artificer are $33.05 of that, and the other seven come to $8.64, so Efficient Construction, Retrofitter Foundry, Ornithopter, Tezzeret and the three removal spells are the cheap place to start. The box's own cards are worth at least $52.80.

Can Urza tap a Thopter that came into play this turn?

Yes. Urza's mana ability taps an artifact as part of Urza's cost, and summoning sickness only stops a creature using its own tap abilities. So two Thopters Sai made this turn can tap for {U}{U}, pay for Sai's draw, and then be sacrificed to it.

Does All Is Dust kill my own Sai?

Yes. Sai is blue, and All Is Dust makes each player sacrifice every permanent with a colour, so he goes, and you can send him to the command zone. In the upgraded 99, thirty-three of the fifty-two nonland permanents are colorless and stay, and so does every Thopter, Myr, Servo and Construct token.

What bracket is Keen Engineering once it's upgraded?

Its floor is still Bracket 1. None of the nine adds is a Game Changer, and there are no extra turns, mass land destruction or tutors in the list. Adding Cyclonic Rift would change that, because it is one, and a single Game Changer puts a deck in Bracket 3.

Is Unwinding Clock worth $22 in a Sai deck?

It's the next card I'd buy after the nine here. It untaps every artifact you control during each other player's untap step, so Urza, Shimmer Dragon and Whirler Rogue can tap the same Thopters on every opponent's turn as well as yours. It's left off the main list because the cheaper adds do more per dollar first.