Cheapest priced copy (Rise of the Eldrazi): $0.35 at Card Kingdom, near mint, their price list as of .
Puncturing Light 
Instant · Common · Shadows over Innistrad · #35
Destroy target attacking or blocking creature with power 3 or less.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Rise of the Eldrazi | 41 | Common | $0.35 | $0.49 |
| Shadows over Innistrad | 35 | Common | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 15 June 2010A “blocking creature” is one that has been declared as a blocker this combat, or one that was put onto the battlefield blocking this combat. Unless that creature leaves combat, it continues to be a blocking creature through the end of combat step, even if the creature or creatures that it was blocking are no longer on the battlefield or have otherwise left combat by then.
- 15 June 2010The power of the targeted creature is checked both as you target it and as Puncturing Light resolves.
- 15 June 2010An “attacking creature” is one that has been declared as an attacker this combat, or one that was put onto the battlefield attacking this combat. Unless that creature leaves combat, it continues to be an attacking creature through the end of combat step.