Bo1 / Best-of-One

Bo1 (Best-of-One) is a match format where a single game determines the winner. There is no sideboard in Bo1 — both players play their main decks from start to finish with no opportunity to adjust between games.

On MTG Arena, Bo1 is the default queue for most ranked formats and the most commonly played mode for daily grinding. Matches are faster, which means more games per session and quicker gold accumulation from daily wins.

How Bo1 Changes Deck Building

Without a sideboard, your main deck has to handle everything on its own. This pushes Bo1 construction toward consistency and broad coverage — strategies that are powerful across a range of matchups, rather than those that rely on specific sideboard cards to shore up bad situations.

Aggressive decks tend to perform well in Bo1 because they are inherently consistent and do not depend on post-sideboard adjustments to win. Control decks can struggle more, since opponents never have the opportunity to bring in targeted pressure or threats that punish a slow game plan.

Hand Smoothing on Arena

Arena applies a hidden hand-smoothing algorithm in Bo1. Each player is effectively presented with the better of two randomly generated opening hands, without knowing this is happening. The result is that mana floods and mana screws are less frequent than in a truly random deal, making the format more consistent than it might otherwise be.

This is worth factoring into deck construction. Because variance is reduced on the low end, you can typically run one or two fewer lands than you might in Bo3 and still hit your curve reliably. It is a small adjustment, but experienced Bo1 players account for it.

Bo1 vs Bo3

Bo1 and Bo3 have separate ranked ladders on Arena, so your rank in one does not affect the other. Bo1 is better suited to grinding daily quests and accumulating gold quickly. Bo3 is the format used in all competitive events — qualifiers and championships run exclusively on Bo3 — so players with competitive ambitions need experience in both.

Neither is objectively better. Many players use Bo1 for volume during the week and Bo3 when they have time for focused, longer sessions. The skills developed in each format are related but distinct enough that practising both is worthwhile.