Cheapest priced copy (Murders at Karlov Manor Commander): $0.59 at Card Kingdom, near mint, their price list as of .
Nadir Kraken 
Creature — Kraken · 2/3 · Rare · The List · #MKC-112
Whenever you draw a card, you may pay {1}. If you do, put a +1/+1 counter on this creature and create a 1/1 blue Tentacle creature token.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
9 printings · $0.59 to $10.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Foundations Jumpstart | 332 | Rare | $0.79 | — |
| Murders at Karlov Manor Commander | 112 | Rare | $0.59 | — |
| March of the Machine Commander | 228 | Rare | $0.59 | — |
| New Capenna Commander | 228 | Rare | $0.59 | — |
| The List | MKC-112 | Rare | — | — |
| Theros Beyond Death Promos | 55p | Rare | $2.49 | $2.99 |
| Theros Beyond Death Promos | 55s | Rare | — | $4.49Out of stock |
| Theros Beyond Death | 55 | Rare | $0.59 | $1.49 |
| Theros Beyond Death | 305 | Rare | $4.49 | $10.99 |
3 rulings from Wizards of the Coast
- 24 January 2020You choose whether to pay {1} after drawing the card and seeing what it is. If you draw multiple cards, you see them all before deciding how many of the resulting triggers you'll pay {1} for.
- 24 January 2020If Nadir Kraken leaves the battlefield after its ability has triggered, you can still pay {1} and get a Tentacle, even though you won't put a +1/+1 counter on Nadir Kraken.
- 24 January 2020While resolving Nadir Kraken's ability, you can't pay {1} multiple times to create multiple Tentacles or to give it multiple +1/+1 counters.