Cheapest priced copy (The List): $0.35 at Card Kingdom, near mint, their price list as of .
Mercy Killing 
Instant · Uncommon · Shadowmoor · #231
Target creature's controller sacrifices it, then creates X 1/1 green and white Elf Warrior creature tokens, where X is that creature's power.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.35 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | SHM-231 | Uncommon | $0.35 | — |
| Shadowmoor | 231 | Uncommon | $0.35 | $7.99 |
One ruling from Wizards of the Coast
- 1 July 2013You target the creature that will be sacrificed when you cast Mercy Killing, then its controller (who may or may not be you) sacrifices it when Mercy Killing resolves. Because this is a sacrifice, neither regeneration nor indestructible will save the creature.