A good cube update changes a handful of cards for a reason you can state, swaps them slot for slot, and gets written down so you can undo it. A bad one adds twenty new cards from the latest set, cuts whatever was nearest to hand, and leaves the group wondering why the Rakdos deck stopped working.
Cubes drift. Every new set brings cards that look better than what you have, drafters ask for their favorites, and a list that was tight three years ago is a loose collection of “good cards” today. This is a process for keeping a weekly cube current without losing the structure that made it fun. It assumes you have a list and have drafted it; if not, start with how to build a cube.
How often should a cube be updated?
Less often than new sets come out. Wizards releases several major sets a year plus supplemental products, and a cube that reacts to every one of them never settles.
A reasonable rhythm for a weekly group:
- Small swaps anytime. One to three cards, when a slot is clearly failing or a new card clearly fills a gap. Announce it and move on.
- A real update every two or three months. Ten to twenty cards, planned, tested, and written up.
- A structural review once a year. Step back and ask whether the archetypes still work, whether the power level has crept, and whether the fixing matches the decks you want.
The point of the slow rhythm is that drafters need to learn the cube. Half the pleasure of a fixed card pool is knowing it. If a quarter of the list changes every month, nobody builds the knowledge that makes cube draft deeper than retail draft.
What should trigger a change?
Not “this new card is good.” Lots of cards are good. The question is whether a specific slot in your cube is underperforming and whether the new card fills that slot better.
Signals a slot needs work:
Late picks. A card that wheels, meaning it comes back around the table, three drafts running is a card nobody wants. Either the slot is overfilled or this is the worst card in it.
Never cast. Drafted, sideboarded, every time. Common with narrow build-arounds and with cards whose archetype is not supported well enough to make them worth playing.
Always cast, always wins. The other failure. A card that goes first pick every draft and the deck it goes into wins the night is a card above your power band. Cut it or raise the band on purpose.
Archetype gaps. You notice during deckbuilding that the Simic ramp drafter has three ramp spells and no payoff, or the aggro drafter has nine two-drops and two one-drops. That is not one card’s fault; it is a count problem. See cube archetypes explained for the counts.
Group feedback. “Can we please cut Blood Moon” said twice by different people is data. The fun test matters as much as the power test.
Keep a running list. A note on your phone works. When you have ten or more entries, you have an update.
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How do you swap cards without wrecking the balance?
Slot for slot. This is the rule that prevents most update damage.
If you cut a white two-drop, add a white two-drop. If you cut a black removal spell, add a black removal spell. If you want to change the structure, meaning add a two-drop and cut a four-drop, do it knowingly and write down why.
A worksheet for each swap:
| Out | In | Slot | Reason | Watch for |
|---|---|---|---|---|
| Benalish Marshal | Adeline, Resplendent Cathar | White 3-drop | Marshal’s WWW was hard to cast; Adeline makes tokens every attack | Adeline too strong for the band? |
| Mind Stone | Talisman of Dominance | Colorless rock | Want fixing, not just ramp | Does it push UB control? |
| Rolling Thunder | Fireblast | Red reach | Aggro needed cheaper finisher | Fireblast dead in midrange? |
Three columns do the work. “Slot” keeps the counts stable. “Reason” makes you defend the change. “Watch for” tells you what to check in the next three drafts.
A few further rules we follow:
- Cap the size. Decide the cube is 360 or 450 or 540 and stay there. “Just one more” is how a 360 becomes a loose 400 that drafts like a worse 450.
- Never cut an archetype’s last piece. If you cut the last free sacrifice outlet, the sacrifice deck stops existing. Check the count before and after.
- Keep the power curve flat. For every card you add that is above the current median, consider whether the new median is where you want it.
- Change one thing at a time in a lane. If you swap six cards in Boros at once and Boros gets worse, you cannot tell which swap did it.
How do you test an update before committing?
Three cheap tests, in order:
Paper decks. Build each of the ten archetypes from the new list on paper, or in CubeCobra’s list view. Do any of them get worse? Does any deck now have two cards that do the same thing and nothing for the slot you emptied?
Bot drafts. CubeCobra and Draftmancer both let you draft the cube against bots. The bots are not people, but a few bot drafts will show you whether the new cards get picked in the range you expect. A card that bots take first every time is probably above your band.
Three live drafts, then judge. Put the changes in, draft three times, and only then look at the results. One draft is noise. A new card that nobody drafts once is not a failure; a new card nobody drafts three times is.
Keep the cut cards in a separate box for at least three months. Half of them come back.
How do you tell the group?
Write a changelog and post it where the group reads. A group chat or Discord channel works; CubeCobra’s blog feature also works and attaches the changes to the list itself.
A changelog entry needs four things:
- Date and summary line. “October update: 14 swaps, mostly aggro support.”
- Out and in, paired. So drafters can see the slot logic.
- One sentence of why, per swap or per theme. Not an essay. “Boros one-drops were short; added two, cut two slow four-drops.”
- What you are watching. This invites feedback on the right things. “Tell me if Adeline feels too strong.”
The changelog has a second job: it is your undo button. In a year, when you want to know why Fireblast is in the cube, the entry is there. Without it, every card’s reason is lost to memory and the list slowly becomes a mystery to its own owner.
What about new sets?
Wait. Read the set reviews from the cube community, note the three to six cards people are excited about, and then do nothing for a month. See which of those cards the public lists on CubeCobra actually added, and which they tried and cut. Then decide whether any fill a slot you have flagged.
The temptation is to add new cards because they are new, which pushes the list toward recent sets and away from the mix of eras that makes a cube feel like a history of the game. A cube that has cards from Alpha next to cards from this year is a better teaching tool and, for most players, more fun to look at.
A good test: if the new card had been printed in 2012, would you still want it? If yes, it earns a slot. If you only want it because it is new, it can wait.
FAQ
How many cards should change in a cube update?
Ten to twenty cards in a planned update every two or three months is a comfortable pace for a 360 cube. Small swaps of one to three cards can happen anytime.
Should I update my cube after every new Magic set?
No. Note the cube-worthy cards, wait a month, and add only those that fill a slot you have already flagged as weak.
What is a cube changelog?
A dated record of every card added and cut, with the reason. Post it to your group and keep it as a way to understand and undo past decisions.
How do I know if a card update was a mistake?
Draft three times and look at pick order, whether the card is cast, and whether its archetype’s results changed. One draft is not enough data.
Change slowly, write it down
The cube your group loves is the one they know. Update it for reasons you can name, swap by slot, test before you commit, and keep the record. Everything else is tinkering. The game is the reason. The people are the point.
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