Rules Ruling · Tournament
Sideboard Rules: 0–10 Cards vs the Old 0/8 — Which Version Applies?
Two versions of the sideboard rule still circulate online: the old “exactly 0 or 8” and the current “0 to 10.” In black and white: TR 2026-07-16 §601.1.c.1. says “10 or fewer cards,” and the official changelog states the cap changed from 8 to 10, effective 2026-07-24. Every claim below cites the official TR.
Citations: TR 2026-07-16 §403（Sideboard 流程與限制）、§601.1.b–601.1.c（構築牌組 40 張、備牌 10 張或以下）· TR July 2026 Update & Changelog（2026-07-24 生效：備牌上限由 8 張改為 10 張，更新 601.1.c.1）
Current version: 10 or fewer (TR §601.1.c)
In competitions where a sideboard is allowed: a player’s sideboard “can include 10 or fewer cards” (TR 601.1.c.1), and it may consist only of valid Main Deck cards (TR 601.1.c.2).
“10 or fewer” means anything from 0 to 10 — you do not have to fill it, unlike the circulating “must be 0 or 8.”
The version question: the old 8 is outdated
The official July 2026 Tournament Rules Update & Changelog states verbatim: “Updated constructed sideboard size from 8 or fewer to 10 or fewer. Updated 601.1.c.1.” — effective 2026-07-24. So the 2026-07-16 TR has exactly one version, 10 or fewer; “0 or 8” is the pre-2026-07-24 rule.
In practice, always follow the rules version your event uses — but 2026-07-16 TR or later means 0–10.
How sideboarding works (TR §403.4, §601.1.c.3–c.4)
- Sideboard cards modify your deck only between games of a match (TR 403.4).
- Cards are exchanged 1-for-1 with Main Deck cards (TR 403.4); after sideboarding the Main Deck must meet deck size — exactly 40 cards in competitions (TR 403.4.c, 601.1.b).
- The 3-copy limit applies to the combined Main Deck and sideboard (TR 601.1.c.3).
- You may change your Chosen Champion to one from your sideboard or main deck that matches your Legend whenever sideboarding would be allowed (TR 601.1.c.4).
Timing and etiquette (TR §403.5–403.10)
- No sideboard cards in the first game of a match (TR 403.5).
- You may count the cards in opponents’ sideboards at any time (TR 403.6).
- You may look at your own sideboard anytime, but must keep it distinguishable (TR 403.7).
- Deck and sideboard must return to their registered states before the first game of the next match (TR 403.8).
- If a game ends in a draw, neither player may sideboard for the next one (TR 403.10).
FAQ
Do I have to run exactly 10 sideboard cards?
No. The current rule is “10 or fewer” (TR 601.1.c.1) — anything from 0 to 10. “0 or 8” is the pre-2026-07-24 rule.
Can I use my sideboard in game one?
No. Sideboarding happens only between games of a match (TR 403.4, 403.5).
How big must my main deck be after sideboarding?
Exactly 40 cards in competitions (TR 601.1.b), so exchanges are 1-for-1 with the main deck (TR 403.4, 403.4.c).
Can I change my Chosen Champion when sideboarding?
Yes — to one from your sideboard or main deck that matches your Legend (TR 601.1.c.4).
May I count my opponent’s sideboard?
Yes, at any time (TR 403.6) — counting only, no looking at contents.
Still unsure?
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