Rivals of Ixalan

Jadelight Ranger | Creature | Merfolk Scout Ranger | When Jadelight Ranger enters the battlefield, it explores, then it explores again. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard. Then repeat this process.) | Jason Rainville

Jungleborn Pioneer | Creature | Merfolk Scout | When Jungleborn Pioneer enters the battlefield, create a 1/1 blue Merfolk creature token with hexproof. (It can't be the target of spells or abilities your opponents control.) | Scott Murphy

Orazca Frillback | Creature | Dinosaur | | Simon Dominic

Swift Warden | Creature | Merfolk Warrior | Flash When Swift Warden enters the battlefield, target Merfolk you control gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.) | Viktor Titov

Thrashing Brontodon | Creature | Dinosaur | {1}, Sacrifice Thrashing Brontodon: Destroy target artifact or enchantment. | Jakub Kasper

Wayward Swordtooth | Creature | Dinosaur | Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.) You may play an additional land on each of your turns. Wayward Swordtooth can't attack or block unless you have the city's blessing. | Chris Rahn

Atzocan Seer | Creature | Human Druid | {T}: Add one mana of any color. Sacrifice Atzocan Seer: Return target Dinosaur card from your graveyard to your hand. | Joseph Meehan

Kumena, Tyrant of Orazca | Legendary Creature | Merfolk Shaman | Tap another untapped Merfolk you control: Kumena, Tyrant of Orazca can't be blocked this turn. Tap three untapped Merfolk you control: Draw a card. Tap five untapped Merfolk you control: Put a +1/+1 counter on each Merfolk you control. | Tyler Jacobson

Jungle Creeper | Creature | Elemental | {3}{B}{G}: Return Jungle Creeper from your graveyard to your hand. | Matt Stewart