Here's what's in the Quandrix Unlimited precon:

DoppelgangDoppelgang

It's mana intensive, but it's so good as a late-game play to completely turn the tables.

Finale of RevelationFinale of Revelation and Thassa's InterventionThassa's Intervention

More X spell card draw is what we need. Intervention doubling as a counterspell is really nice, too.

Ripples of PotentialRipples of Potential and Evolution SageEvolution Sage

I thought the deck could use a bit more proliferation for the +1/+1 counters. We don't do any other landfall stuff, but we should expect to at least play one every turn, so Evolution Sage works. Ripples of Potential doubling as a protection spell is great.

Unnatural RestorationUnnatural Restoration and Evolution WitnessEvolution Witness

The precon didn't have any graveyard recursion. These both fit perfectly with our strategy.

Swiftfoot BootsSwiftfoot Boots

Zimone is a value engine, and likely to get targeted. I want her to have a more permanent means of protection.

Wave GoodbyeWave Goodbye

This is the kind of board wipe we should be playing in this deck. Not "Choose odd or even, blah blah blah."

Wilderness ReclamationWilderness Reclamation

There are enough X spell instants in the deck that Wilderness Reclamation is a worthy inclusion.

Kalonian HydraKalonian Hydra and Zimone, Paradox SculptorZimone, Paradox Sculptor

More counters!

Champion of LambholtChampion of Lambholt and Emil, Vastlands RoamerEmil, Vastlands Roamer

With these two creatures we're looking to make combat much more deadly. Champion is basically a win condition. Speaking of...

Simic AscendancySimic Ascendancy

How could they not include this in the precon? Probably because it's a bit too easy. But hey, games gotta end.

NexosNexos and Nyxbloom AncientNyxbloom Ancient

More mana from our lands for bigger X spells.

Kodama of the West TreeKodama of the West Tree and SporocystSporocyst

More lands so we can get more mana from our lands for bigger X spells.

MathemagicsMathemagics, Geometer's ArthropodGeometer's Arthropod, TerrasymbiosisTerrasymbiosis

More card draw.

Branching EvolutionBranching Evolution, The Earth CrystalThe Earth Crystal, Vorinclex, Monstrous RaiderVorinclex, Monstrous Raider

More counters.

The Great HengeThe Great Henge

More card draw, more mana, more counters, and, what the heck, throw in some lifegain too. The Great Henge does it all.

The OzolithThe Ozolith

We worked so hard to get all those counters. Would be a shame if they went away. Enter: The Ozolith.

Mutational AdvantageMutational Advantage

Mutational Advantage is a really nice protection spell for counters decks. It also proliferates!

Walking BallistaWalking Ballista and Herald of Secret StreamsHerald of Secret Streams

More ways to win! We're not gonna be comboing out with Walking Ballista like other decks might, but it'll sure be nice to deal lots of damage with it. And Herald removes the math from combat.

The deck has enough math already, am I right?

This precon was pretty difficult to make cuts for. To get to my self-imposed 15 cuts, I had to make some difficult choices. But still, cut we must.

Goldvein HydraGoldvein Hydra

Tapped Treasure tokens when it dies....yay? This Hydra is underwhelming, even with all its keyword abilities.

Mana BloomMana Bloom

As far as ramp goes, this is kind of awful. Even if it does synergize with the deck.

Primo, the UnboundedPrimo, the Unbounded, Lattice LibraryLattice Library, and Deekah, Fractal TheoristDeekah, Fractal Theorist

We already got X spells and +1/+1 counters going on, and plenty of creature cards to play. I think we can forgo the whole Fractal token subtheme.

Hangarback WalkerHangarback Walker

We'll skip Thopter tokens too.

Zimone, Quandrix ProdigyZimone, Quandrix Prodigy and Zimone, All-QuestioningZimone, All-Questioning

All five of the Secrets of Strixhaven precons shoehorned older Strixhaven legends into them. If you've checked out the other upgrade guides, you'll see we ended up cutting most of them, since they just don't fit. Same applies here to these younger Zimones.

What's really annoying is that the one Zimone that does fit our strategy, Zimone, Paradox SculptorZimone, Paradox Sculptor, wasn't included.

OversimplifyOversimplify, Perplexing TestPerplexing Test, and Zimone's HypothesisZimone's Hypothesis

These are all either really bad (Oversimplify) or really situational (the other two). None of them really work here. Wave GoodbyeWave Goodbye is so much better.

Beast WithinBeast Within

The deck was too heavy on removal, and we just don't need this. Nothing against the card; it's a classic.

Fractal HarnessFractal Harness

We ditched the Fractal subtheme, and we're really not doing Equipment. Doubling the counters on the equipped creature is nice, but it also puts a target on that creature. I'd rather not have to spend the equip cost over and over.

Quandrix ApprenticeQuandrix Apprentice

We're replacing this with the much better - for this deck, anyway - Geometer's ArthropodGeometer's Arthropod.

Guardian AugmenterGuardian Augmenter

I wanted a more permanent solution for Zimone, so we replaced this with Swiftfoot BootsSwiftfoot Boots.