How does a sideboard work at a Riftbound tournament?

Most matches at a tournament of Riftbound: the League of Legends trading card game are the best of three games, and a sideboard lets a player change their deck between those games. It is a small set of extra cards that the player brings along with the deck and keeps apart from it during play. After the first game, a player knows which deck sits across the table and can swap in the cards that do best against it.

The rule numbers below are those of the Riftbound Tournament Rules of 9 October 2026, which Riot publishes on its Rules Hub.

What can a sideboard hold?

In Constructed, a sideboard holds up to 10 cards, and each of them has to be a card the Main Deck could legally play (rules 601.1.c.1 and 601.1.c.2). That means units, gear and spells within the two domains of the Legend, and no banned cards. Runes, battlefields and Legends have no place in it, because those stay as registered for the whole event (rule 403.4.b).

The limit of three copies of a name counts the Main Deck and the sideboard together (rule 601.1.c.3). A deck with one Ferrous Forerunner in the Main Deck may keep two more in the sideboard, but not three.

The Tournament Rules allow a sideboard only in certain competitions (rule 403.1), so check the event page or ask the organizer before a store event. At Competitive and Professional events, the sideboard goes on the decklist with the rest of the deck before the first round, and the list cannot change after that (rules 401.1 to 401.4).

When can you use your sideboard?

A sideboard is used only between the games of a match. No sideboard card may be played in the first game (rule 403.5). After each game, both players may swap cards before the next game is set up, and before the next match the deck goes back to its registered state (rules 406.1.a and 403.8). After a drawn game, neither player may sideboard for the game that follows (rule 403.10).

A Constructed event played as the best of one game has no time between games, but its head judge may use a setup that brings it closer to best of three (rule 406.1.h). Each player puts out their Legend, one of each player's three battlefields is picked at random and the first player is settled. Both players may then sideboard, as they would between games of a best-of-three match, before they set out their chosen champions and shuffle.

How do you swap cards in Constructed?

Every card that comes in from the sideboard replaces one card of the Main Deck, so the Main Deck stays at exactly 40 cards and the sideboard keeps its size (rules 403.4, 403.4.c and 601.1.b). A player who brings in two answers to gear takes out two cards that do little against that opponent. If you sleeve your deck, sleeve the sideboard cards the same way, since the cards you swap in have to match the sleeves of the Main Deck (rule 422.2).

The chosen champion may change as well, to another champion unit from the Main Deck or the sideboard that matches the Legend (rules 403.4.a and 601.1.c.4). An Irelia deck led by Blade Dancer that starts with Irelia, Fervent as its chosen champion may switch to Irelia, Graceful for the next game, provided the deck or its sideboard holds a copy.

What makes a good sideboard card?

A good sideboard card is strong against some decks and weak against the rest, so it waits outside the Main Deck until the right opponent comes along. The six Decree spells of Vendetta show the idea: each costs 1 or 2 Energy and is aimed at one domain, so against a deck without that domain it has nothing to do.

• Decree of Rage deals 4 to an enemy Calm unit.
• Decree of Focus gives a friendly unit +4 Might for the turn when that unit is in combat with an enemy Fury unit or is chosen by an enemy Fury spell.
• Decree of Insight gives an enemy Body unit 5 less Might for the turn.
• Decree of Strength makes an opponent reveal their hand, and you choose a Mind card in it for them to recycle.
• Decree of Discord returns enemy Order units with a total Might of 5 or less to their owners' hands.
• Decree of Unity kills an enemy Chaos unit or gear.

Riot's report on RQ Los Angeles, the last Regional Qualifier of 2026, held on 25 to 27 September 2026, shows how top players fill the space: every decklist in it has a sideboard of exactly 10 cards. DSG Prismaticism won with Pridestalker, the Legend of Rengar in Fury and Body. His sideboard held two Brittle Steel and a Noxian Demolitionist to kill gear, two Decree of Strength against Mind decks, and more copies of three cards from his Main Deck. The runner-up, Xeno, played Blade Dancer, the Legend of Irelia, with two Adaptatron and two Ravenbloom Prefect in the sideboard, both of which deal with gear.

The two lists follow a pattern worth copying: answers to a kind of card only some decks play, cards aimed at one domain, and extra copies of cards that matter more against certain decks. The full lists are in Riot's report on the event.

What happens if you forget to reset your deck?

Starting a new match with sideboard cards still in the Main Deck is a Deck Presentation Error, and its penalty is a Warning (rule 703.4.a.2). A judge puts the deck right where that is still possible. The penalty becomes a Game Loss when someone other than the player who made the mistake finds it after the opening hands are drawn, or when the deck can no longer be put right (rules 703.4.c.3 and 703.4.c.4). The Tournament Rules give the example of a player who had already drawn both copies of Traveling Merchant, one of which belonged in the sideboard.

A registered list with more than three copies of a card between the Main Deck and the sideboard is a Decklist Error, with a Game Loss as its penalty (rule 703.3.a.3). The safest habit is to put every sideboard card back the moment a match ends and to count both piles before the next round. Your opponent may count the cards in your sideboard at any time as well (rule 403.6).

How does a sideboard work in Sealed and Draft?

In Sealed and Draft, where players build a deck from packs opened at the event, the sideboard is every card of your pool that is not in your deck (rules 602.4.a.7 and 602.4.b.8). The swaps do not have to be one for one, because that rule covers Constructed only (rule 403.4). Between games you may even change the domains, runes, Legend and chosen champion of the deck, as long as it keeps the rules of the format, such as a Main Deck of at least 25 cards in Sealed or 20 in Draft.

At Competitive and Professional events, you register a starting deck, with the rest of the pool as its sideboard, and every match begins with that deck (rule 602.3.e). At casual events such as a Pre-Rift event, you may change the deck freely between games and matches unless the head judge says otherwise (rule 602.3.f).

Do you need a sideboard for your first tournament?

No, a sideboard is optional, and a player new to tournaments can play the same Main Deck in every game. Once you know your deck well, a sideboard is the simplest way to improve against the decks you expect to meet. Pick two or three answers for each deck that beats you often, and write down which cards go out for each. Between games you may read written notes you made before the match until the opening hands are drawn, without showing them to the opponent (rule 416.5).

Which cards to hold back depends on the decks you expect to meet, so it pays to know which decks are strong in the current meta before you pick them. Single cards for a sideboard come from local game stores, from Cardmarket in Europe, from TCGplayer in the United States and from CardTrader on both sides of the Atlantic. The shared decks show what other players bring, and the event finder lists the Riftbound events near you.