Cheapest priced copy (Murders at Karlov Manor): $0.35 at Card Kingdom, near mint, their price list as of .
Karlov Watchdog 
Creature — Dog · 3/2 · Uncommon · Murders at Karlov Manor · #20
Vigilance
Permanents your opponents control can't be turned face up during your turn.
Whenever you attack with three or more creatures, creatures you control get +1/+1 until end of turn.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Murders at Karlov Manor | 20 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 2 February 2024While Karlov Watchdog is on the battlefield, opponents can't attempt to turn face-down creatures face up either by paying a disguise or morph cost or by paying the mana cost of a cloaked or manifested creature.
- 2 February 2024It doesn't matter what happens to the creatures in response. As long as you attacked with at least three creatures, creatures you control will get +1/+1 until end of turn when Karlov Watchdog's triggered ability resolves.