Soul of Eternity

Mana cost: {5}{W}{W}
Type: Creature — Avatar
Power / toughness: * / *
Set: Commander Legends #626 (rare)
Price: $1.37 USD

Soul of Eternity's power and toughness are each equal to your life total.
Encore {7}{W}{W} ({7}{W}{W}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Soul of Eternity has 4 printings, first in Commander Legends (2020). EDHREC ranks it #9,786 among Commander cards. It appears most in Trostani, Selesnya's Voice decks (3,769 on EDHREC). 1 public deck on TCG runs it. It has 8 official rulings.

Legality

commander: legal
legacy: legal
vintage: legal
pauper: not legal
modern: not legal
pioneer: not legal
standard: not legal
brawl: not legal

Public decks that run Soul of Eternity

Hatsune Miku - Secret Lair Commander, led by Trostani, Selesnya's Voice

Commanders that run Soul of Eternity most

Deck counts from EDHREC.

Trostani, Selesnya's Voice: 3,769 decks
Brion Stoutarm: 2,570 decks
Evra, Halcyon Witness: 513 decks
Dynaheir, Invoker Adept: 172 decks
Halfdane: 16 decks

Often played with Soul of Eternity

Cards that show up in the same decks on EDHREC.

Rulings

2020-11-10: 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.
2020-11-10: Opponents who have left the game aren't counted when determining how many tokens to create.
2020-11-10: 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.
2020-11-10: 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.
2020-11-10: Each token must attack the appropriate player if able.
2020-11-10: The ability that defines Soul of Eternity's power and toughness functions in all zones, not just the battlefield.
2020-11-10: 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.
2023-07-28: 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.