Theros

Artisan of Forms | Creature | Human Wizard | Heroic — Whenever you cast a spell that targets Artisan of Forms, you may have Artisan of Forms become a copy of target creature, except it has this ability. | Min Yum

Benthic Giant | Creature | Giant | Hexproof (This creature can't be the target of spells or abilities your opponents control.) | Jaime Jones

Breaching Hippocamp | Creature | Horse Fish | Flash (You may cast this spell any time you could cast an instant.) When Breaching Hippocamp enters the battlefield, untap another target creature you control. | Christopher Burdett

Coastline Chimera | Creature | Chimera | Flying {1}{W}: Coastline Chimera can block an additional creature this turn. | Dan Scott

Crackling Triton | Creature | Merfolk Wizard | {2}{R}, Sacrifice Crackling Triton: It deals 2 damage to any target. | Greg Staples

Horizon Scholar | Creature | Sphinx | Flying When Horizon Scholar enters the battlefield, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.) | Karl Kopinski

Master of Waves | Creature | Merfolk Wizard | Protection from red Elemental creatures you control get +1/+1. When Master of Waves enters the battlefield, create a number of 1/0 blue Elemental creature tokens equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.) | Karl Kopinski

Meletis Charlatan | Creature | Human Wizard | {2}{U}, {T}: The controller of target instant or sorcery spell copies it. That player may choose new targets for the copy. | Jason A. Engle

Mnemonic Wall | Creature | Wall | Defender When Mnemonic Wall enters the battlefield, you may return target instant or sorcery card from your graveyard to your hand. | Trevor Claxton

Nimbus Naiad | Enchantment Creature | Nymph | 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. | David Palumbo

Omenspeaker | Creature | Human Wizard | When Omenspeaker enters the battlefield, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.) | Dallas Williams

Prescient Chimera | Creature | Chimera | Flying Whenever you cast an instant or sorcery spell, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.) | Daarken

Prognostic Sphinx | Creature | Sphinx | Flying Discard a card: Prognostic Sphinx gains hexproof until end of turn. Tap it. Whenever Prognostic Sphinx attacks, scry 3. | Steve Prescott

Sealock Monster | Creature | Octopus | Sealock Monster can't attack unless defending player controls an Island. {5}{U}{U}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.) When Sealock Monster becomes monstrous, target land becomes an Island in addition to its other types. | Adam Paquette

Shipbreaker Kraken | Creature | Kraken | {6}{U}{U}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.) When Shipbreaker Kraken becomes monstrous, tap up to four target creatures. Those creatures don't untap during their controllers' untap steps for as long as you control Shipbreaker Kraken. | Jack Wang

Thassa, God of the Sea | Legendary Enchantment Creature | God | 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. | Jason Chan

Thassa's Emissary | Enchantment Creature | Crab | Bestow {5}{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.) Whenever Thassa's Emissary or enchanted creature deals combat damage to a player, draw a card. Enchanted creature gets +3/+3. | Sam Burley

Triton Fortune Hunter | Creature | Merfolk Soldier | Heroic — Whenever you cast a spell that targets Triton Fortune Hunter, draw a card. | Clint Cearley

Triton Shorethief | Creature | Merfolk Rogue | | Howard Lyon

Vaporkin | Creature | Elemental | Flying Vaporkin can block only creatures with flying. | Seb McKinnon

Wavecrash Triton | Creature | Merfolk Wizard | Heroic — Whenever you cast a spell that targets Wavecrash Triton, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step. | Ryan Barger

Returned Phalanx | Creature | Zombie Soldier | Defender {1}{U}: Returned Phalanx can attack this turn as though it didn't have defender. | Seb McKinnon

Agent of Horizons | Creature | Human Rogue | {2}{U}: Agent of Horizons can't be blocked this turn. | Clint Cearley

Battlewise Hoplite | Creature | Human Soldier | Heroic — Whenever you cast a spell that targets Battlewise Hoplite, put a +1/+1 counter on Battlewise Hoplite, then scry 1. (To scry 1, look at the top card of your library, then you may put that card on the bottom of your library.) | Willian Murai

Daxos of Meletis | Legendary Creature | Human Soldier | Daxos of Meletis can't be blocked by creatures with power 3 or greater. Whenever Daxos of Meletis deals combat damage to a player, exile the top card of that player's library. You gain life equal to that card's mana value. Until end of turn, you may cast that card and you may spend mana as though it were mana of any color to cast that spell. | Karla Ortiz

Medomai the Ageless | Legendary Creature | Sphinx | Flying Whenever Medomai the Ageless deals combat damage to a player, take an extra turn after this one. Medomai the Ageless can't attack during extra turns. | David Palumbo

Shipwreck Singer | Creature | Siren | Flying {1}{U}: Target creature an opponent controls attacks this turn if able. {1}{B}, {T}: Attacking creatures get -1/-1 until end of turn. | Daarken

Spellheart Chimera | Creature | Chimera | Flying, trample Spellheart Chimera's power is equal to the number of instant and sorcery cards in your graveyard. | Svetlin Velinov

Horizon Chimera | Creature | Chimera | Flash Flying, trample Whenever you draw a card, you gain 1 life. | Sam Burley

Prophet of Kruphix | Creature | Human Wizard | Untap all creatures and lands you control during each other player's untap step. You may cast creature spells as though they had flash. | Winona Nelson