Cheapest priced copy (Exodus): $3.49 at Card Kingdom, near mint, their price list as of .
Slaughter 
Instant · Uncommon · Exodus · #74
Buyback—Pay 4 life. (You may pay 4 life in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.)
Destroy target nonblack creature. It can't be regenerated.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Exodus | 74 | Uncommon | $3.49 | — |
One ruling from Wizards of the Coast
- 4 October 2004You can’t pay the buyback if you have less than 4 life, even if an effect would keep you from losing for having 0 or less life.