Cheapest priced copy (Murders at Karlov Manor): $0.35 at Card Kingdom, near mint, their price list as of .
Sumala Sentry 
Creature — Elf Archer · 1/3 · Uncommon · Murders at Karlov Manor · #233
Reach
Whenever a face-down permanent you control is turned face up, put a +1/+1 counter on it and a +1/+1 counter on this creature.
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 | 233 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 2 February 2024If the permanent that was turned face up is no longer on the battlefield when Sumala Sentry's triggered ability resolves, you'll still put a +1/+1 counter on Sumala Sentry. Similarly, if Sumala Sentry is no longer on the battlefield, you'll still put a +1/+1 counter on the permanent that turned face up.