Dragon's Claw

Whenever a player casts a red spell, you may gain 1 life.

Negate

Mirror-Mad Phantasm

Flying
{1}{U}: Mirror-Mad Phantasm's owner shuffles it into their library. If that player does, they reveal cards from the top of that library until a card named Mirror-Mad Phantasm is revealed. The player puts that card onto the battlefield and all other cards revealed this way into their graveyard.

Snakeform

Until end of turn, target creature loses all abilities and becomes a green Snake with base power and toughness 1/1.
Draw a card.

Deadeye Navigator

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Deadeye Navigator is paired with another creature, each of those creatures has "{1}{U}: Exile this creature, then return it to the battlefield under your control."

Sea Serpent

Sea Serpent can't attack unless defending player controls an Island.
When you control no Islands, sacrifice Sea Serpent.

Merfolk Spy

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.

Stormtide Leviathan

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.

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Serpent of the Endless Sea

Serpent of the Endless Sea's power and toughness are each equal to the number of Islands you control.
Serpent of the Endless Sea can't attack unless defending player controls an Island.

Downsize

Target creature you don't control gets -4/-0 until end of turn.
Overload {2}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Psychic Venom

Enchant land
Whenever enchanted land becomes tapped, Psychic Venom deals 2 damage to that land's controller.

Loxodon Warhammer

Equipped creature gets +3/+0 and has trample and lifelink.
Equip {3}

Angelic Armaments

Equipped creature gets +2/+2, has flying, and is a white Angel in addition to its other colors and types.
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)

Volition Reins

Enchant permanent
When Volition Reins enters, if enchanted permanent is tapped, untap it.
You control enchanted permanent.

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Ongoing Investigation

Whenever one or more creatures you control deal combat damage to a player, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{1}{G}, Exile a creature card from your graveyard: Investigate. You gain 2 life.

Mask of Avacyn

Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {3}

Island

Chasm Skulker

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.)

Precursor Golem

When Precursor Golem enters, create two 3/3 colorless Golem artifact creature tokens.
Whenever a player casts an instant or sorcery spell that targets only a single Golem, that player copies that spell for each other Golem that spell could target. Each copy targets a different one of those Golems.

Hexplate Golem

Neurok Invisimancer

Neurok Invisimancer can't be blocked.
When Neurok Invisimancer enters, target creature can't be blocked this turn.

Darksteel Axe

Indestructible (Effects that say "destroy" don't destroy this artifact.)
Equipped creature gets +2/+0.
Equip {2}

Tranquil Cove

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {W} or {U}.

Triton Shorethief

Back from the Brink

Exile a creature card from your graveyard and pay its mana cost: Create a token that's a copy of that card. Activate only as a sorcery.

Elixir of Immortality

{2}, {T}: You gain 5 life. Shuffle Elixir of Immortality and your graveyard into their owner's library.

Stone Golem

Harbor Serpent

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.

Mind Control

Enchant creature
You control enchanted creature.

Frostwind Invoker

Flying
{8}: Creatures you control gain flying until end of turn.

Dirgur Nemesis

Defender
Megamorph {6}{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.)

Levitation

Elgaud Shieldmate

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Elgaud Shieldmate is paired with another creature, both creatures have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Turn to Frog

Until end of turn, target creature loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Ghastly Haunting

Soul Seizer

Flying
When Soul Seizer deals combat damage to a player, you may transform it. If you do, attach it to target creature that player controls.

Soul Seizer // Ghastly Haunting

Razorfield Rhino

Metalcraft — Razorfield Rhino gets +2/+2 as long as you control three or more artifacts.

Tamiyo's Journal

At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{T}, Sacrifice three Clues: Search your library for a card, put that card into your hand, then shuffle.