Sliver Gravemother

If an effect stops a token from attacking a specific player, that token can attack any player, planeswalker, or battle, 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.

While the "legend rule" doesn't apply to Slivers you control, you can control any number of legendary Slivers with the same name and none of them will be put into the graveyard.

If you control more than one legendary Sliver with the same name and the "legend rule" begins applying to them again (perhaps because Sliver Gravemother leaves the battlefield) you'll immediately have to comply with the rule and put all but one of those Slivers into the graveyard.

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.

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.

Opponents who have left the game aren't counted when determining how many tokens to create.