Loops

Tournament Rules section 505 — 21 rules. From Riot's Tournament Rules for sanctioned events, last updated October 9, 2026.

505.1.: Some sequences of actions can be repeated and are shortcutted as a loop.
505.2.: Each iteration of a loop must contain identical, non-conditional actions performed on the same set of cards. To establish a loop, the looping player must be able to say with certainty exactly what each step of the loop will be, not just the outcome.
505.2.a.: Loops must be fully deterministic; they may not rely on probability, decision trees, or conditional actions. Example:
505.2.a.1.: Legal Loop: With enough Energy available, playing Grim Apothecary to a battlefield then using its trigger to return itself to hand 100 times.
505.2.a.2.: Illegal Loop: A card reads "Recycle 3 cards from your trash: Ready a unit." A player with enough Energy available wants to use this to recycle 2 copies of Stupefy from their trash and 1 copy of Downstage Dramatics with an additional copy of Dramatics in hand, planning to play the Downstage Dramatics from hand, and then play each card as they draw it until there are 3 cards in the trash for them to recycle.
505.2.a.2.a.: This is a non-deterministic loop because the order you play the cards is not guaranteed. If the loop only included copies of the same exact card draw spell, it would be deterministic.
505.2.b.: Players can manually execute non-deterministic loops, but must do so in a timely fashion. Failure to do so is Slow Play. See 703.2 for more information on Slow Play.
505.3.: To decide how to proceed with a loop, determine how many players are needed to maintain it (who must take actions or make decisions to sustain the loop):
505.3.a.: No players
505.3.b.: One player
505.3.c.: Two or more players
505.4.: For each maintaining player (if any), in turn order, that player chooses a number of iterations.
505.5.: Each other player (if any), in turn order, may choose to agree to that number or choose a number of iterations after which they commit to taking action to break the loop or choose not to break the loop.
505.6.: If no player chooses to break the loop and there were no maintaining players, the game ends in a draw.
505.7.: Otherwise, the loop continues until the lowest number of iterations chosen, then that player either gains priority (if a maintaining player) or breaks the loop.
505.8.: If a player intervenes to break a loop, they may choose to interrupt a partially completed iteration.
505.9.: If a sequence of actions is non-deterministic, it may not be shortcut and iterations must be performed manually.
505.10.: Some loops are maintained by decisions rather than actions. In these cases, apply 505.4-505.8 but with the player making a different decision rather than a different action.
505.11.: Judges are the final arbiter of what constitutes a loop, or if choices are available to continue a loop when secret information is involved.
505.12.: Players who try to opt-out of shortcutting or propose incorrect shortcutting to use up time are cheating. See 704.8 for more information about cheating.
505.13.: Players cannot use loops to stall. When other actions are available, attempting to perform a loop that doesn’t change the game state is cheating. See 704.8 for more information about cheating.