Cheapest priced copy (Fourth Edition): $0.35 at Card Kingdom, near mint, their price list as of .
Blood Lust 
Instant · Common · Fifth Edition · #212
If target creature has toughness 5 or greater, it gets +4/-4 until end of turn. Otherwise, it gets +4/-X until end of turn, where X is its toughness minus 1.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
5 printings · $0.35 to $17.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fourth Edition Foreign Black Border | 178 | Common | — | — |
| Fourth Edition | 178 | Common | $0.35 | — |
| Fifth Edition | 212 | Common | $0.35 | — |
| Legends | 135 | Uncommon | $17.99 | — |
| Renaissance | 75 | Uncommon | — | — |
One ruling from Wizards of the Coast
- 1 November 2005Has changed slightly in functionality, with the old continuous nature of the toughness reduction gone away; the toughness change remains static. For example, if you have three Swamps and Nightmare on the battlefield and then cast Blood Lust on it, it will become 7/1. If one of your Swamps is subsequently destroyed, your Nightmare will become 6/0 and be put in the graveyard.