Eumidian Wastewaker

Encore is an activated ability that functions from the graveyard. “Encore [cost]” means “[Cost], Exile this card from your graveyard: For each opponent, create a token that’s a copy of this card that attacks that opponent this turn if able. The tokens gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.”

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.

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.

Each token must attack the appropriate player if able.

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.