
Dauntless River Marshal | Creature | Human Soldier | Dauntless River Marshal gets +1/+1 as long as you control an Island.
{3}{U}: Tap target creature. | Mark Winters

Aeronaut Tinkerer | Creature | Human Artificer | Aeronaut Tinkerer has flying as long as you control an artifact. (It can't be blocked except by creatures with flying or reach.) | Willian Murai

Amphin Pathmage | Creature | Salamander Wizard | {2}{U}: Target creature can't be blocked this turn. | Mark Winters

Chasm Skulker | Creature | Squid Horror | 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.) | Jack Wang

Chief Engineer | Creature | Vedalken Artificer | Artifact spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting an artifact spell pays for {1} or one mana of that creature's color.) | Steven Belledin

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

Diffusion Sliver | Creature | Sliver | Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}. | Trevor Claxton

Frost Lynx | Creature | Elemental Cat | When Frost Lynx enters the battlefield, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step. | Izzy

Fugitive Wizard | Creature | Human Wizard | | Mark Zug

Glacial Crasher | Creature | Elemental | Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Glacial Crasher can't attack unless there is a Mountain on the battlefield. | Mark Winters

Illusory Angel | Creature | Angel Illusion | Cast this spell only if you've cast another spell this turn.
Flying | Allen Williams

Jalira, Master Polymorphist | Legendary Creature | Human Wizard | {2}{U}, {T}, Sacrifice another creature: Reveal cards from the top of your library until you reveal a nonlegendary creature card. Put that card onto the battlefield and the rest on the bottom of your library in a random order. | Steve Prescott

Jorubai Murk Lurker | Creature | Leech | Jorubai Murk Lurker gets +1/+1 as long as you control a Swamp.
{1}{B}: Target creature gains lifelink until end of turn. (Damage dealt by the creature also causes its controller to gain that much life.) | Clint Cearley

Kapsho Kitefins | Creature | Fish | Flying
Whenever Kapsho Kitefins or another creature enters the battlefield under your control, tap target creature an opponent controls. | Ryan Yee

Master of Predicaments | Creature | Sphinx | Flying
Whenever Master of Predicaments deals combat damage to a player, choose a card in your hand. That player guesses whether the card's mana value is greater than 4. If the player guessed wrong, you may cast the card without paying its mana cost. | Matt Stewart

Mercurial Pretender | Creature | Shapeshifter | You may have Mercurial Pretender enter the battlefield as a copy of a creature you control, except it has "{2}{U}{U}: Return this creature to its owner's hand." | Izzy

Nimbus of the Isles | Creature | Elemental | Flying (This creature can't be blocked except by creatures with flying or reach.) | Cliff Childs

Paragon of Gathering Mists | Creature | Human Wizard | Other blue creatures you control get +1/+1.
{U}, {T}: Another target blue creature you control gains flying until end of turn. | Michael C. Hayes

Quickling | Creature | Faerie Rogue | Flash (You may cast this spell any time you could cast an instant.)
Flying
When Quickling enters the battlefield, sacrifice it unless you return another creature you control to its owner's hand. | Clint Cearley

Research Assistant | Creature | Human Wizard | {3}{U}, {T}: Draw a card, then discard a card. | Svetlin Velinov

Soul of Ravnica | Creature | Avatar | Flying
{5}{U}{U}: Draw a card for each color among permanents you control.
{5}{U}{U}, Exile Soul of Ravnica from your graveyard: Draw a card for each color among permanents you control. | Stephan Martiniere

Stormtide Leviathan | Creature | 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. | Karl Kopinski

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

Welkin Tern | Creature | Bird | Flying (This creature can't be blocked except by creatures with flying or reach.)
Welkin Tern can block only creatures with flying. | Austin Hsu

Sliver Hivelord | Legendary Creature | Sliver | Sliver creatures you control have indestructible. (Damage and effects that say "destroy" don't destroy them.) | Aleksi Briclot