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.
705.3 An effect may state that a coin flip has a certain result and/or that a certain player wins a coin flip. In that case, ignore the actual results of that flip and use the indicated results instead. This can cause a player to win a flip that couldn’t otherwise be won.