Cheapest priced copy (Conspiracy: Take the Crown): $0.35 at Card Kingdom, near mint, their price list as of .
Goblin Tunneler 
Creature — Goblin Rogue · 1/1 · Common · Duel Decks: Merfolk vs. Goblins · #49
{T}: Target creature with power 2 or less can't be blocked this turn.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
5 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Conspiracy: Take the Crown | 160 | Common | $0.35 | $0.49 |
| Duel Decks: Merfolk vs. Goblins | 49 | Common | $0.35 | — |
| Magic 2011 | 143 | Common | $0.35 | $0.49 |
| Magic 2012 | 142 | Common | $0.35 | $0.49 |
| Rise of the Eldrazi | 148 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 15 June 2010The ability doesn’t grant an ability to the targeted creature. Rather, it affects the game rules and states something that’s now true about that creature. After the ability resolves, the creature can’t be blocked that turn even if it loses all abilities.
- 15 June 2010The power of the targeted creature is checked both as you target it and as the ability resolves. After the ability resolves, the creature can’t be blocked that turn even if its power becomes greater than 2.