Cheapest priced copy (Final Fantasy Commander): $0.69 at Card Kingdom, near mint, their price list as of .
Chasm Skulker 
Creature — Squid Horror · 1/1 · Rare · Magic 2015 · #46
Whenever you draw a card, put a +1/+1 counter on this creature.
When this creature dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on this creature. (They can't be blocked as long as defending player controls an Island.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
9 printings · $0.69 to $32.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Bloomburrow Commander | 164 | Rare | $0.79 | — |
| Commander 2016 | 85 | Rare | $1.79 | — |
| Commander Legends: Battle for Baldur's Gate | 714 | Rare | $0.79 | — |
| Final Fantasy Commander | 262 | Rare | $0.69 | $3.99 |
| Magic 2015 | 46 | Rare | $1.29 | $11.99 |
| March of the Machine Commander | 218 | Rare | $0.99 | — |
| New Capenna Commander | 214 | Rare | $0.79 | — |
| The List | M15-46 | Rare | $0.99 | — |
| Magic 2015 Promos | 46p | Rare | $11.99 | $32.99 |
2 rulings from Wizards of the Coast
- 18 July 2014If you draw multiple cards, the first ability will trigger that many times. Each of these abilities will cause a +1/+1 counter to be put on Chasm Skulker.
- 18 July 2014If enough -1/-1 counters are put on Chasm Skulker at the same time to make its toughness 0 or less, the number of +1/+1 counters on it before it got any -1/-1 counters will be used to determine how many Squid tokens you get. For example, if there are two +1/+1 counters on Chasm Skulker and it gets three -1/-1 counters, you'll get two Squid tokens.