Cheapest priced copy (Murders at Karlov Manor): $0.35 at Card Kingdom, near mint, their price list as of .
Case of the Pilfered Proof 
Enchantment — Case · Uncommon · Murders at Karlov Manor · #9
Whenever a Detective you control enters or is turned face up, put a +1/+1 counter on it.
To solve — You control three or more Detectives. (If unsolved, solve at the beginning of your end step.)
Solved — If one or more tokens would be created under your control, those tokens plus a Clue token are created instead. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
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 | 9 | Uncommon | $0.35 | $0.49 |
14 rulings from Wizards of the Coast
- 2 February 2024You can't sacrifice a Clue to pay multiple costs. For example, you can't sacrifice a Clue token to activate its own ability and also to activate Alquist Proft, Master Sleuth's ability.
- 2 February 2024The meaning of "solved" differs based on what type of ability follows it. "Solved — [activated ability]" means "[Activated ability]. Activate only if this Case is solved." Activated abilities contain a colon. They're generally written "[Cost]: [Effect]."
- 2 February 2024Being solved is not part of a permanent's copiable values. A permanent that becomes a copy of a solved Case is not solved. A solved Case that somehow becomes a copy of a different Case stays solved.
- 2 February 2024"Solved — [static ability]" means "As long as this Case is solved, [static ability]." Static abilities are written as statements, such as "Creatures you control get +1/+1" or "Instant and sorcery spells you cast cost {1} less to cast."
- 2 February 2024Some spells and abilities that investigate may require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won't resolve. You won't create any Clue tokens.
- 2 February 2024Cases don't lose their other abilities when they become solved.
- 2 February 2024Some abilities trigger "whenever you sacrifice a Clue". Those abilities trigger whenever you sacrifice a Clue for any reason, not just to activate a Clue's activated ability.
- 2 February 2024"To Solve — [condition]" means "At the beginning of your end step, if [condition] and this Case is not solved, it becomes solved."
- 2 February 2024Once a Case becomes solved, it stays solved until it leaves the battlefield.
- 2 February 2024Each Case has two special keyword abilities: to solve and solved.
- 2 February 2024Clue is an artifact type. Even though it appears on some cards with other permanent types, it's never a creature type, a land type, or anything but an artifact type.
- 2 February 2024"Solved — [Triggered ability]" means "[Triggered ability]. This ability triggers only if this Case is solved." Triggered abilities use the word "when," "whenever," or "at." They're often written as "[Trigger condition], [effect]."
- 2 February 2024If an effect refers to a Clue, it means any Clue artifact, not just a Clue artifact token. For example, you can sacrifice Wrench to pay for Alquist Proft, Master Sleuth's activated ability.
- 2 February 2024"To solve" abilities will check for their condition twice: once when the ability would trigger, and once when it resolves. If the condition isn't true at the beginning of your end step, the ability won't trigger at all. If the condition isn't true when the ability resolves, the Case won't become solved.