Cheapest priced copy (Tempest): $0.35 at Card Kingdom, near mint, their price list as of .
Watchdog 
Artifact Creature — Dog · 1/2 · Uncommon · Tempest · #314
This creature blocks each combat if able.
As long as this creature is untapped, all creatures attacking you get -1/-0.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tempest | 314 | Uncommon | $0.35 | — |
One ruling from Wizards of the Coast
- 1 April 2008The second ability is no longer triggered. It continuously checks the tapped/untapped status of the Watchdog, and gives them -1/-0 as appropriate.