Random

Some cards and rules will ask for a decision to be made at random. Beyond the plain English definition of the word, several rules offer further guidance as to how these decisions should be made.

Description

Mark Rosewater has described randomness as a state that, if not interfered with, has unpredictability.

Randomness is first introduced to the game when each player shuffles their libraries before the game. While the Comprehensive Rules state only that libraries must be in a state such that no player knows their order, the Tournament Rules go into substantially more detail. Notably, the Tournament Rules state that pile shuffling alone is not adequate. Additionally, players must have the option of performing a final shuffle of their opponent's deck. At the Competitive and Professional Rules Enforcement Levels, players must shuffle their opponents decks.

The Tournament Rules suggest a die roll or coin toss as a random method for determining which player will play first in the first game of a match.

When flipping a coin, other sources of randomness are allowed, as long as there are two outcomes of equal likelihood and all players agree to that substitution.

Rules

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 701.18a To “scry N” means to look at the top N cards of your library, then put any number of them on the bottom of your library in any order and the rest on top of your library in any order.

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 705. Flipping a Coin
  • 705.1. Some cards refer to flipping a coin. A coin used in a flip must be a two-sided object with easily distinguished sides and equal likelihood that either side lands face up. If the coin that’s being flipped doesn’t have an obvious “heads” or “tails,” designate one side to be “heads,” and the other side to be “tails.” Other methods of randomization may be substituted for flipping a coin as long as there are two possible outcomes of equal likelihood and all players agree to the substitution. For example, the player may roll an even-sided die and call “odds” or “evens,” or roll an even-sided die and designate that “odds” means “heads” and “evens” means “tails.”
  • 705.2. Some effects that instruct a player to flip a coin care only about whether the coin comes up heads or tails. No player wins or loses a coin flip for this kind of effect. For all other effects that instruct a player to flip a coin, the player that flips the coin calls “heads” or “tails.” If the call matches the result, the player wins the flip. Otherwise, the player loses the flip. Only the player who flips the coin wins or loses the flip; no other players are involved.