Keyword: Landwalk

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Harbor Serpent can’t attack unless there are five or more Islands on the battlefield.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can’t attack.

Trample
Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Shroud (This creature can’t be the target of spells or abilities.)

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Harbor Serpent can’t attack unless there are five or more Islands on the battlefield.

Bloodthirst 1 (If an opponent was dealt damage this turn, this creature enters the battlefield with a +1/+1 counter on it.)
Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)

Islandwalk, swampwalk (This creature can’t be blocked as long as defending player controls an Island or a Swamp.)
Whenever Wrexial, the Risen Deep deals combat damage to a player, you may cast target instant or sorcery card from that player’s graveyard without paying its mana cost. If that spell would be put into a graveyard this turn, exile it instead.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Harbor Serpent can’t attack unless there are five or more Islands on the battlefield.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Whenever Merfolk Spy deals combat damage to a player, that player reveals a card at random from their hand.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can’t attack.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
: Regenerate River Boa.

Level up (: Put a level counter on this. Level up only as a sorcery.)
LEVEL 1-4
0/6
LEVEL 5+
6/6
Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Whenever Thada Adel, Acquisitor deals combat damage to a player, search that player’s library for an artifact card and exile it. Then that player shuffles their library. Until end of turn, you may play that card.

Multikicker (You may pay an additional any number of times as you cast this spell.)
Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Enclave Elite enters the battlefield with a +1/+1 counter on it for each time it was kicked.

Islandwalk, swampwalk (This creature can’t be blocked as long as defending player controls an Island or a Swamp.)
Whenever Wrexial, the Risen Deep deals combat damage to a player, you may cast target instant or sorcery card from that player’s graveyard without paying its mana cost. If that spell would be put into a graveyard this turn, exile it instead.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
: Tap target creature without flying.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
: Regenerate River Boa.

First strike; legendary landwalk (This creature can’t be blocked as long as defending player controls a legendary land.)

Trample
Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Shroud (This creature can’t be the target of spells or abilities.)

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost less to cast.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
When Inkfathom Divers enters the battlefield, look at the top four cards of your library, then put them back in any order.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
When Merrow Harbinger enters the battlefield, you may search your library for a Merfolk card, reveal it, then shuffle your library and put that card on top of it.

Islandwalk (This creature can’t be blocked as long as defending player controls an Island.)
: Target Merfolk you control gains protection from the color of your choice until end of turn.

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