Rivals of Ixalan

Aquatic Incursion | Enchantment | | When Aquatic Incursion enters the battlefield, create two 1/1 blue Merfolk creature tokens with hexproof. (They can't be the targets of spells or abilities your opponents control.) {3}{U}: Target Merfolk can't be blocked this turn. | Jason Rainville

Riverwise Augur | Creature | Merfolk Wizard | When Riverwise Augur enters the battlefield, draw three cards, then put two cards from your hand on top of your library in any order. | Alayna Danner

Siren Reaver | Creature | Siren Pirate | Raid — This spell costs {1} less to cast if you attacked this turn. Flying | Tomasz Jedruszek

Deadeye Brawler | Creature | Human Pirate | Deathtouch Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.) Whenever Deadeye Brawler deals combat damage to a player, if you have the city's blessing, draw a card. | Jesper Ejsing