Impulsivity

Since you are using an alternative cost to cast the spell, you can't pay any other alternative costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, you must pay those.

Each token must attack the appropriate player if able.

If the spell you cast has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

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."

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.

Exiling the card with encore is a cost to activate the encore 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.