Cheapest priced copy (Visions): $0.35 at Card Kingdom, near mint, their price list as of .
Dwarven Vigilantes 
Creature — Dwarf · 2/2 · Common · Visions · #77
Whenever this creature attacks and isn't blocked, you may have it deal damage equal to its power to target creature. If you do, this creature assigns no combat damage this turn.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Visions | 77 | Common | $0.35 | — |
One ruling from Wizards of the Coast
- 15 April 2013An ability that triggers when something “attacks and isn’t blocked” triggers in the declare blockers step after blockers are declared if (1) that creature is attacking and (2) no creatures are declared to block it. It will trigger even if that creature was put onto the battlefield attacking rather than having been declared as an attacker in the declare attackers step.