Cheapest priced copy (Foundations Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Vanguard Seraph 
Creature — Angel Warrior · 3/3 · Common · Foundations · #28
Flying
Whenever you gain life for the first time each turn, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Foundations Commander | 56 | Common | $0.35 | — |
| Foundations | 28 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 8 November 2024If you gain life during a turn before Vanguard Seraph is on the battlefield, its last ability won't trigger that turn even if you gain life again later in the turn.
- 8 November 2024Vanguard Seraph's last ability triggers just once for your first life-gaining event on each turn, no matter how much life you gain.