Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
11/4/2015 The term “defending player” in the myriad rules (or any other ability of an attacking creature) refers to the player the creature with myriad was attacking at the time it became an attacking creature this combat, or the controller of the planeswalker the creature was attacking at the time it became an attacking creature this combat.
11/4/2015 If the defending player is your only opponent, no tokens are put onto the battlefield.
11/4/2015 You choose whether each token is attacking the player or a planeswalker they control as the token is created.
11/4/2015 Although the tokens enter the battlefield attacking, they were never declared as attackers. Abilities that trigger whenever a creature attacks won’t trigger, including the myriad ability of the tokens. If there any costs to have a creature attack, those costs won’t apply to the tokens.
11/4/2015 The token creatures all enter the battlefield at the same time.
11/4/2015 Each token copies exactly what was printed on the original creature and nothing else. It doesn’t copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.
11/4/2015 Any enters-the-battlefield abilities of the copied creature will trigger when the token enters the battlefield. Any “as [this permanent] enters the battlefield” or “[this permanent] enters the battlefield with” abilities of the copied creature will also work.
11/4/2015 If myriad creates more than one token for any given player (due to an effect such as the one Doubling Season creates), you may choose separately for each token whether it’s attacking the player or a planeswalker they control.