Cheapest priced copy (Tenth Edition): $0.35 at Card Kingdom, near mint, their price list as of .
Stun 
Instant · Common · Invasion · #172
Target creature can't block this turn.
Draw a card.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
3 printings · $0.35 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tenth Edition | 240 | Common | $0.35 | $4.99 |
| Invasion | 172 | Common | $0.35 | $7.99 |
| Tempest | 207 | Common | $0.35 | — |
2 rulings from Wizards of the Coast
- 4 October 2004Must be used before blockers are declared in order to affect blocking decisions. You can’t wait to see what your opponent declares and then try to stop them.
- 4 October 2004You can use it after combat or even on a creature which can’t possibly block this turn because it’s that player’s turn to attack, but it generally has no effect other than to let you draw a card.