Cheapest priced copy (Commander Legends): $0.35 at Card Kingdom, near mint, their price list as of .
First Response 
Enchantment · Uncommon · Commander Legends · #22
At the beginning of each upkeep, if you lost life last turn, create a 1/1 white Soldier creature token.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 22 | Uncommon | $0.35 | $0.49 |
| Magic 2015 | 12 | Uncommon | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 10 November 2020The Soldier won't be able to attack the turn it's created (unless something gives it haste).
- 10 November 2020First Response looks at the entire previous turn to determine whether its ability triggers or not. It doesn't matter whether First Response was on the battlefield when you lost life.
- 10 November 2020First Response checks only if you lost life during the turn, not whether your life total decreased over the course of the turn. For example, if you lost 2 life and then gained 8 life last turn, First Response's ability will trigger.
- 10 November 2020Damage dealt to you causes you to lose that much life.
- 10 November 2020Only one Soldier will be created no matter how much life was lost.