Horizon Scholar

Flying
When this creature enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Curate

Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Draw a card.

Striped Riverwinder

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Cycling {U} ({U}, Discard this card: Draw a card.)

Take into Custody

Tap target creature. It doesn't untap during its controller's next untap step.

Cold-Water Snapper

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Chain to Memory

Target creature gets -4/-0 until end of turn. Scry 2.

Aether Spellbomb

{U}, Sacrifice this artifact: Return target creature to its owner's hand.
{1}, Sacrifice this artifact: Draw a card.

Cleric of Chill Depths

Whenever this creature blocks a creature, that creature doesn't untap during its controller's next untap step.

Deliberate

Angler Drake

Flying
When this creature enters, you may return target creature to its owner's hand.

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Island

Omen of the Sea

Flash (You may cast this spell any time you could cast an instant.)
When this enchantment enters, scry 2, then draw a card.
{2}{U}, Sacrifice this enchantment: Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Coralhelm Guide

{4}{U}: Target creature can't be blocked this turn.

Witching Well

When this artifact enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)
{3}{U}, Sacrifice this artifact: Draw two cards.

Dive Down

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Bind the Monster

Enchant creature
When this Aura enters, tap enchanted creature. It deals damage to you equal to its power.
Enchanted creature doesn't untap during its controller's untap step.

Orazca Puzzle-Door

{1}, {T}, Sacrifice this artifact: Look at the top two cards of your library. Put one of those cards into your hand and the other into your graveyard.

River Sneak

This creature can't be blocked.
Whenever another Merfolk you control enters, this creature gets +1/+1 until end of turn.

Coral Merfolk

Shore Keeper

{7}{U}, {T}, Sacrifice this creature: Draw three cards.

Flood of Recollection

Return target instant or sorcery card from your graveyard to your hand. Exile Flood of Recollection.

Shaper Apprentice

This creature has flying as long as you control another Merfolk.

Wall of Runes

Defender (This creature can't attack.)
When this creature enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)