Chasm Skulker is a rare Creature — Squid Horror card from Magic 2015 Promos (PM15), collector number 46p. Current market price: $12.06 (foil $14.31), 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.)