Cheapest priced copy (Murders at Karlov Manor Commander): $1.29 at Card Kingdom, near mint, their price list as of .
Tangletrove Kelp 
Artifact Creature — Clue Plant · 6/6 · Rare · Murders at Karlov Manor Commander · #334
Ward {2}
At the beginning of each combat, other Clues you control become 6/6 Plant creatures in addition to their other types until end of turn.
{2}, Sacrifice this creature: Draw a card.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $1.29 to $1.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Murders at Karlov Manor Commander | 24 | Rare | $1.29 | — |
| Murders at Karlov Manor Commander | 334 | Rare | $1.79 | — |
7 rulings from Wizards of the Coast
- 2 February 2024Clues you control will keep any abilities they previously had while they’re creatures.
- 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 2024If a Clue you control is already a creature when Tangletrove Kelp’s second ability resolves, Tangletrove Kelp’s second ability will overwrite any previous effects that set that creature’s power and toughness to specific numbers. Effects that otherwise modify its power and toughness will still apply no matter when they took effect. The same is true for +1/+1 counters.
- 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 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 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 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.