Custodian of the Trove

Defender
Custodian of the Trove enters tapped.

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Nimbus Naiad

Bestow {4}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Flying
Enchanted creature gets +2/+2 and has flying.

Refocus

Armory of Iroas

Whenever equipped creature attacks, put a +1/+1 counter on it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Dissolve

Counter target spell. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Index

Look at the top five cards of your library, then put them back in any order.

Psychic Barrier

Counter target creature spell. Its controller loses 1 life.

Triton Shorestalker

Mind Sculpt

Mistform Wall

Mistform Wall has defender as long as it's a Wall.
{1}: Mistform Wall becomes the creature type of your choice until end of turn.

Thassa, God of the Sea

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
{1}{U}: Target creature you control can't be blocked this turn.

Wall of Frost

Defender
Whenever Wall of Frost blocks a creature, that creature doesn't untap during its controller's next untap step.

Divination

Murmuring Phantasm

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.

Trepanation Blade

Whenever equipped creature attacks, defending player reveals cards from the top of their library until they reveal a land card. The creature gets +1/+0 until end of turn for each card revealed this way. That player puts the revealed cards into their graveyard.
Equip {2}

Negate

Updraft Elemental

Curse of the Bloody Tome

Enchant player
At the beginning of enchanted player's upkeep, that player mills two cards.

Island

Reduce in Stature

Enchant creature
Enchanted creature has base power and toughness 0/2.

Coral Barrier

Defender (This creature can't attack.)
When Coral Barrier enters, create a 1/1 blue Squid creature token with islandwalk. (It can't be blocked as long as defending player controls an Island.)

Sidisi's Faithful

Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi's Faithful exploits a creature, return target creature to its owner's hand.

Cloudfin Raptor

Flying
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Illusory Angel

Cast this spell only if you've cast another spell this turn.
Flying

Cancel

Ring of Evos Isle

{2}: Equipped creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's blue.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Kraken Hatchling

Sigiled Starfish

{T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Phantom Warrior

Doorkeeper

Defender
{2}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender.

Tome Scour

Chronomaton

{1}, {T}: Put a +1/+1 counter on Chronomaton.

Gudul Lurker

Gudul Lurker can't be blocked.
Megamorph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)