Chasm Skulker

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.)

Pioneer Masters

Bloomburrow Commander

Whenever you draw a card, put a +1/+1 counter on Chasm Skulker.
When Chasm Skulker dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on Chasm Skulker. (They can't be blocked as long as defending player controls an Island.)

March of the Machine Commander

Commander Legends: Battle for Baldur's Gate

If 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.

If 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.

Squid

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)