River Sneak

River Sneak can't be blocked.
Whenever another Merfolk enters the battlefield under your control, River Sneak gets +1/+1 until end of turn.

Lord of Atlantis

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Deepchannel Mentor

Blue creatures you control can't be blocked.

Cold-Eyed Selkie

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.

Tangled Islet

({T}: Add {G} or {U}.)
Tangled Islet enters the battlefield tapped.

Forest

Mist-Cloaked Herald

Counterspell

Aspect of Mongoose

Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)
When Aspect of Mongoose is put into a graveyard from the battlefield, return Aspect of Mongoose to its owner's hand.

Remote Isle

Remote Isle enters the battlefield tapped.
{T}: Add {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Island

Cancel

Tranquil Thicket

Tranquil Thicket enters the battlefield tapped.
{T}: Add {G}.
Cycling {G} ({G}, Discard this card: Draw a card.)

Unsummon

Return target creature to its owner's hand.

Hydra's Growth

Enchant creature
When Hydra's Growth enters the battlefield, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.