Cheapest priced copy (Crimson Vow Commander): $0.79 at Card Kingdom, near mint, their price list as of .
Ethereal Investigator 
Creature — Spirit · 2/3 · Rare · Murders at Karlov Manor Commander · #105
Flying
When this creature enters, investigate X times, where X is the number of opponents you have. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you draw your second card each turn, create a 1/1 white Spirit creature token with flying.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
3 printings · $0.79 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Murders at Karlov Manor Commander | 105 | Rare | $0.99 | — |
| Crimson Vow Commander | 12 | Rare | $0.79 | — |
| Crimson Vow Commander | 50 | Rare | $1.49 | — |