Cheapest priced copy (Kaladesh): $0.35 at Card Kingdom, near mint, their price list as of .
Essence Extraction 
Instant · Uncommon · The List · #KLD-80
Essence Extraction deals 3 damage to target creature and you gain 3 life.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Kaladesh | 80 | Uncommon | $0.35 | $0.49 |
| Kaladesh Promos | 80 | Uncommon | $0.35 | — |
| The List | KLD-80 | Uncommon | $0.35 | — |
One ruling from Wizards of the Coast
- 20 September 2016If the target creature becomes an illegal target, Essence Extraction doesn't resolve and you don't gain life.