Cheapest priced copy (Commander Legends: Battle for Baldur's Gate): $0.35 at Card Kingdom, near mint, their price list as of .
Mystery Key 
Artifact — Equipment · Uncommon · The List · #CLB-85
When equipped creature deals combat damage to a player, sacrifice this Equipment. If you do, draw three cards.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends: Battle for Baldur's Gate | 85 | Uncommon | $0.35 | $0.49 |
| The List | CLB-85 | Uncommon | $0.35 | — |