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The short answer
Only the stated exception applies
Rulebreaker gives a deckbuilding exception only when that card is your commander, before play begins. It does not itself change the commander’s color identity. Other restrictions still apply unless the ability explicitly changes them.
Mystery Booster Commander Edition release notes ↗Does Rulebreaker change my commander’s color identity?
No—not merely by allowing more cards into your deck. Tolabow remains blue; Seluma remains white. The extra cards permitted by their abilities do not add colors to the commander.
Keep three questions separate: what may go in the deck, the commander’s color identity, and what mana a particular permanent produces.
Can Command Tower or Arcane Signet make extra colors?
With Tolabow alone: normally blue only. Choosing red for its spell exception does not change that. With Seluma alone, normally white only.
These abilities use the commander’s identity. A Mountain can instead provide red in a Tolabow deck because its basic-land clause admits that card.
Assumes no other effect changes the mana abilities. Our application of the official card text and color-identity rules.
The Draft fallback emblem is a separate case. Check more Tolabow mana sources.
What does each commander allow?
| Commander | Allowed exception | Still restricted |
|---|---|---|
| Seluma, Light of Aysen | Angel cards of any color identity; any basic lands. | Other card types, singleton and the usual 100-card total. |
| Whtz, the Bibliophile | No maximum deck size. | Off-color cards and unrestricted duplicates. |
| Tolabow, Loch Rascal | One chosen extra color in instant/sorcery identities; any basic lands. | Other card types do not receive the spell exception. |
Seluma example: one Fallen Angel fits; two copies still violate singleton. Official examples · Try Tolabow’s card examples
Common questions
Does it apply from the ninety-nine?
No. The release notes restrict the deck-construction effect to a card designated as your commander.
Does losing my commander remove the deckbuilding permission?
No. The release notes make this a pregame deck-construction effect. Removing the commander during play does not retroactively make the starting deck illegal.
Can I use the draft partner exception in a normal Commander game?
The special partner permission belongs to MBC Commander Draft. It does not automatically change constructed Commander. See the draft guide.
When does it apply? Rules-version details
The ability works before play begins, when you designate the card as commander. The August release notes already describe that behavior.
Checked rules: September 25, 2026. October 19 changes are announced, not verified as effective at our October 21 review.
Rules version and official references
The official rules page linked the September document at our review. The October bulletin describes planned release changes; its publication date is not an effective date.
Checked rules · October bulletin · Latest rules pageThe October bulletin proposes 903.5e for Rulebreaker. In the checked September rules, that number still concerns sideboards.
Which other restrictions stay in place?
Only the restriction named by the ability changes. Check singleton, deck size and format legality separately. Explain your commander’s exception before the game; it does not grant the MBC Draft partner permission in ordinary Commander.
Official sources & review notes
Checked October 21, 2026. Follow the original publications for later updates.
Optional buying checks
Optional checks for cards and supplies discussed in this guide. No store links, affiliate links or paid placements.
Seluma, Light of Aysen
For the Angel color-identity exception explained in this guide.
Whtz, the Bibliophile
For the deck-size exception, rather than an extra-color permission.
Use cards and supplies you already own when possible.
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