Cheapest priced copy (Commander Legends): $0.99 at Card Kingdom, near mint, their price list as of .
Seraphic Greatsword 
Artifact — Equipment · Mythic · Commander Legends · #45
Equipped creature gets +2/+2.
Whenever equipped creature attacks the player with the most life or tied for most life, create a 4/4 white Angel creature token with flying that's tapped and attacking that player.
Equip {4}
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.99 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 45 | Mythic | $0.99 | $1.49 |
| Commander Legends | 624 | Mythic | $3.49 | $2.99 |
3 rulings from Wizards of the Coast
- 10 November 2020Seraphic Greatsword's triggered ability won't trigger if the equipped creature attacks a planeswalker controlled by the player with the most life.
- 10 November 2020Once the triggered ability triggers, it doesn't matter what happens to players' life totals before the ability resolves. You'll create an Angel token even if the player the equipped creature attacked doesn't have the most life as the ability resolves.
- 10 November 2020Although the Angel token created by the triggered ability is attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example).