Chasm Skulker is a rare Creature — Squid Horror card from The List (PLST), collector number M15-46. Current market price: $1.00, TCGplayer market prices via Scryfall.
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.)