Cheapest priced copy (Ravnica Allegiance): $0.39 at Card Kingdom, near mint, their price list as of .
Resolute Watchdog 
Creature — Dog · 1/3 · Uncommon · Ravnica Allegiance · #19
Defender
{1}, Sacrifice this creature: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.39 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica Allegiance | 19 | Uncommon | $0.39 | $2.49 |
One ruling from Wizards of the Coast
- 25 January 2019Resolute Watchdog can be the target of its own ability. The ability won’t resolve since it won’t have a legal target, and no creature will gain indestructible, but this does allow you to sacrifice Resolute Watchdog without another creature to target if you want to.