MTG Cube Design Lessons from Caleb Gannon: Goals, Interaction, and the Low-Curve Lever

“Make it fun” is the most dangerous sentence in cube design, because it gives you zero help on pick #43 when you’re staring at three cards you like and only one of them actually belongs.

Caleb Gannon’s Everything I Have Learned About Cube Design is basically a field manual for getting out of that trap. The through-line is simple: get brutally specific about your design goals, then use a few big levers (especially interactivity and mana curve) to make the whole environment snap into focus.

https://www.youtube.com/calebgannon

TLDR

Write goals you can use at the card level, not vibes like “fun” or “high power.”
Interactivity is a north-star goal, not just “add more removal.” It’s about decision density and players having agency.
Lowering the curve is a huge lever because it turns expensive “bombs” into cheaper, flexible pieces that create games instead of ending them.
Power is context-dependent, so every add or cut changes what the rest of the cube “means.”
Support what you want to happen, and cut “cool” cards that never actually get played.

Why “Caleb Gannon cube design” advice hits different

Caleb isn’t just saying “run good cards.” His work on the Powered Synergy Cube is about building an environment where decks win by being a deck, not by resolving a single standalone haymaker. That leads him to prioritize interactivity, flexibility, flatter power, and a deliberately low curve, even inside a high-power shell. That combination is exactly why his cube sparked so much broader discussion about whether synergy and interaction can coexist.

Step 1: Design goals have to answer “Why?” (and then get more specific)

Caleb’s starting point is deceptively basic: if you can’t clearly answer why your cube exists, you can’t make consistent cuts. “Fun” is too broad, because it lets in a bunch of cards that are individually sweet but collectively incoherent.

A useful Caleb-style goal has two traits:

It describes gameplay, not card quality
It’s specific enough to exclude cards you personally like

In his own process, he narrowed toward goals like:

Interactivity
Flexibility
Flat power level (fewer game-ending bombs)
…and then noticed a consequence: the environment naturally started pulling toward cheaper, more interactive spells, so he made “keep the mana curve low” an explicit goal.

That move matters, because once “low curve” is a goal, you can stop arguing with yourself about every random six-drop you miss from your favorite format. It’s not “is this card cool,” it’s “does this card help my environment do the thing I said it does?”

Step 2: Interactivity is not a card count, it’s a play pattern

A lot of cubes say they want interaction, then accidentally build “ships passing in the night” because the interaction is either too narrow, too expensive, or doesn’t line up with the threats that matter.

Caleb’s version of interactivity is more like:

Players get to respond to each other’s plan
The key turns have meaningful choices
Games aren’t decided by one unanswered card

Here’s a practical way to translate that into cube decisions:

Prefer interactive pieces that also do other jobs. The more cards can function in multiple matchups and archetypes, the more often games involve real decisions instead of “did you draw the one answer.”
Make engine pieces answerable, especially in synergy-forward environments. If the cube is about assembling engines, then disrupting engines has to be a real thing people can do.
Be careful with “free win” threats. If a single card provides advantage, board presence, and a win condition all by itself, it tends to reduce interactivity because the correct response becomes “have the answer now or lose.” This is worth considering for printed proxies or original cube cards.

The interactivity toolbelt (the stuff that creates agency)

Cheap disruption (so you can contest early engines)
Broad answers (so interaction actually lines up with the threats)
Combat relevance (so blocking, racing, and sequencing matter)
Counterplay windows (so players can plan around what might happen next)

Step 3: Curve lowering is the cleanest “environment dial” you can turn

If you only steal one idea from the whole Caleb Gannon cube design approach, steal this: lowering the mana curve changes everything.

When you reduce the number of expensive spells, a few things happen at once:

Players spend less time doing “nothing,” so games have more decision points.
“Bombs” get replaced by cheaper, flexible, interactive components, which naturally increases interactivity.
Synergy decks get to play Magic earlier, instead of hoping they live long enough to assemble their thing.

Caleb frames this as a goal that “substantially narrowed the context” of the cube. That narrowing is a feature. It stops your list from being pulled in ten directions by nostalgia, power creep, or “but this card is iconic.”

A table you can actually use: goals, levers, and what you give up

Design goal (name it)	What you want drafts to feel like	Primary levers to pull	What you give up
More interactivity	Games hinge on decisions, not topdecks	Cheaper disruption, answerable engines, fewer standalone wincons	Some “spectacle” moments
More flexibility	Picks stay open longer, fewer dead cards	Mono-colored utility, overlap pieces, fewer narrow gold cards	Some sharp archetype identity
Flatter power	Fewer “oops I win” turns	Trim planeswalker piles and haymakers, reward engines not solos	Some classic power highs
Lower curve	More early plays, more sequencing	Cut top-end, add 1–3 MV glue, tighten mana	Big-mana “battlecruiser” games
Synergy first	Decks win by cohesion	Density math, redundancy, avoid trap enablers	Raw rate cards that ignore synergy

The important part is that every lever has a cost. The cube gets better by being more itself, not by trying to do everything.

Step 4: Power is context-dependent, so every change rewrites the cube

Caleb’s blunt warning: cards don’t have fixed power levels. They’re powerful in an environment. Change the environment and the same card can go from busted to embarrassing (or vice versa).

That’s why “micro-tuning” can lie to you. If you keep swapping one card at a time without a north-star goal, you can get stuck in endless churn because the target keeps moving.

A useful mental model is:

Adding a card isn’t only “this card is good.”
It’s also “this makes a whole class of other cards worse.”

So when you add something like an efficient ping or cheap removal upgrade, you’re not just buffing red. You might also be nerfing 1-toughness mana dorks, token makers, or an entire creature-based archetype. Sometimes that’s correct. Sometimes it silently murders the deck you meant to support.

Step 5: “Fun” cards that never get played are not actually fun

This one hurts, because it targets every cube designer’s “pet package.”

Caleb’s point is pragmatic: if the deck doesn’t come together naturally, the payoff card is basically fictional. Players don’t experience the fun you imagined, they experience packs with cards they can’t take and sideboards full of “maybe someday.”

This is where his advice pairs perfectly with curve-lowering:

Lower curves help decks do their thing more often.
Better interaction helps games stay contested without ending to a haymaker.
More flexible glue pieces reduce the number of “dead” picks.

If you want a synergy environment, you are signing up for one hard responsibility: make the synergy happen often enough that people believe in it.

Step 6: Use density math, not vibes

Once you know your goals, you can do what Caleb recommends: build an “ideal version” of an archetype deck, then work backward into how many of each component needs to exist in the list so that deck shows up at a reasonable frequency.

He gives a rough method for estimating “how many of a thing a player can expect to see” based on how much of the cube is drafted and how many players share a color. It’s not perfect math, but it’s a fantastic reality check when a deck consistently ends up short on removal, fixing, or enablers.

Step 7: Beware “secondary enablers,” the classic synergy trap

Caleb calls out a specific kind of card that looks like synergy support but often plays like a do-nothing: secondary enablers.

These are cards that:

do nothing by themselves,
require you to already have drafted enough of the right stuff,
cost a bunch of mana,
and only then start paying you back.

They’re not always wrong, but they’re easy to overrate, especially if your cube already has enough moving parts. If your environment is synergy-heavy, secondary enablers can become the reason decks stumble, because players spend turns investing in “setup” instead of impacting the game.

A quick “Caleb Gannon cube design” self-check

If you’re mid-rebuild, ask these and be honest:

Can I state my cube goals in one sentence that excludes cards?
Do games involve meaningful interaction before turn 4?
Are my win conditions mostly “build a machine,” not “resolve one card”?
Is my curve doing what I think it’s doing, or am I secretly a 5-drop cube?
Do synergy decks assemble reliably without forcing?
Are my narrow cards sending clear signals, or just creating dead picks?
Did I add any “trap” secondary enablers recently?
When something underperforms, is it the card, or is it the environment?

FAQs

Is lowering the curve always good for MTG cube design?

No. It’s a lever, not a law. Lower curves usually increase decision density and reduce “draw-go until bomb,” but they can also make games more tempo-driven and punish slow synergy plans if the interaction is too efficient.

How do I make a synergy cube interactive without killing synergy?

Aim interaction at engine points, not just generic “kill everything.” Also make sure synergy decks have resilient lines and redundancy. A format can support synergy and interaction, but only if you intentionally balance both.

What’s the biggest beginner mistake Caleb’s advice helps avoid?

Building on vibes. “This seems fun” leads to a pile. “This cube is about X, so I’m cutting Y” leads to an environment.

How do I know if my curve is too high?

If games routinely hinge on who resolves the first big spell, or if players spend early turns doing nothing meaningful, your top-end might be crowding out the cheap glue and interaction that creates real games.

Do I need to do density math for every archetype?

Not forever, but it’s worth doing at least once for your most important decks. It will immediately expose where you’re under-supporting something you claim to support.