Encore

Encore is a keyword ability specifically used in the Commander format. Encore was introduced in Commander Legends. It has similarities with unearth, flashback, and myriad.

Description
Encore is effective in two-player duels but really shines in multiplayer games.

Encore is an activated ability that can be activated only if the creature card that has it is in your graveyard. It only appears on non-legendary creatures. You can pay a creature's encore cost and exile it from your graveyard to create a number of token copies of it equal to your number of opponents. Each of those tokens has haste, must attack that player, and is sacrificed during the end step.

Rulings

 * Exiling the card with encore is a cost to activate the ability. Once you announce that you're activating it, no player may take actions until you've finished. They can't try to remove the card from your graveyard to stop you from paying the cost.
 * Opponents who have left the game aren't counted when determining how many tokens to create.
 * The tokens copy only what's on the original card. Effects that modified that creature when it was previously on the battlefield won't be copied.
 * Each token must attack the appropriate player if able.
 * If one of the tokens can't attack for any reason (such as being tapped), then it doesn't attack. If there's a cost associated with having it attack, you aren't forced to pay that cost, so it doesn't have to attack in that case either.
 * If an effect stops a token from attacking a specific player, that token can attack any player or planeswalker, or not attack at all. If the effect stops the token from attacking a specific player unless a cost is paid, you don't have to pay that cost unless you want to attack that player.
 * If one of the tokens somehow is under another player's control as the delayed triggered ability resolves, you can't sacrifice that token. It remains on the battlefield indefinitely, even if you regain control of it later.