Cheapest priced copy (Murders at Karlov Manor): $0.49 at Card Kingdom, near mint, their price list as of .
Cryptex 
Artifact · Rare · Murders at Karlov Manor Promos · #251p
{T}, Collect evidence 3: Add one mana of any color. Put an unlock counter on this artifact. (To collect evidence 3, exile cards with total mana value 3 or greater from your graveyard.)
Sacrifice this artifact: Surveil 3, then draw three cards. Activate only if this artifact has five or more unlock counters on it.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
4 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Murders at Karlov Manor | 251 | Rare | $0.49 | $0.49 |
| Murders at Karlov Manor | 422 | Rare | $0.49 | $0.49 |
| Murders at Karlov Manor Promos | 251p | Rare | $0.49 | $0.79 |
| Murders at Karlov Manor Promos | 251s | Rare | — | $0.69 |
3 rulings from Wizards of the Coast
- 2 February 2024Once you've announced that you're casting a spell, players can't take actions until you've finished doing so. Notably, opponents can't try to remove cards from your graveyard to stop you from collecting evidence.
- 2 February 2024Cryptex's first ability is a mana ability. It doesn't use the stack and can't be responded to.
- 2 February 2024If you can't exile enough cards to meet or exceed the required mana value, you can't choose to collect evidence at all.