Cheapest priced copy (Duskmourn: House of Horror Commander): $0.79 at Card Kingdom, near mint, their price list as of .
Shriekwood Devourer 
Creature — Treefolk · 7/5 · Rare · Duskmourn: House of Horror Commander · #62
Trample
Whenever you attack with one or more creatures, untap up to X lands, where X is the greatest power among those creatures.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.79 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duskmourn: House of Horror Commander | 35 | Rare | $0.79 | — |
| Duskmourn: House of Horror Commander | 62 | Rare | $1.49 | — |
2 rulings from Wizards of the Coast
- 20 September 2024Creatures that enter attacking were never declared as attackers, so Shriekwood Devourer's last ability won't take them into account.
- 20 September 2024The value of X is calculated only once, as Shriekwood Devourer's last ability resolves. This means that the value of X may be different than you had hoped when attackers were declared if attacking creatures have left the battlefield or their power has changed.