Last Updated: 2026-10-09
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.