Cheapest priced copy (Commander 2019): $0.49 at Card Kingdom, near mint, their price list as of .
Trail of Mystery 
Enchantment · Rare · Duskmourn: House of Horror Commander · #203
Whenever a face-down creature you control enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Whenever a permanent you control is turned face up, if it's a creature, it gets +2/+2 until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
5 printings · $0.49 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2019 | 186 | Rare | $0.49 | — |
| Duskmourn: House of Horror Commander | 203 | Rare | $0.49 | — |
| Khans of Tarkir | 154 | Rare | $0.49 | $0.49 |
| Murders at Karlov Manor Commander | 192 | Rare | $0.49 | — |
| Khans of Tarkir Promos | 154s | Rare | — | $0.99 |