Rivals of Ixalan

Cacophodon | Creature | Dinosaur | Enrage — Whenever Cacophodon is dealt damage, untap target permanent. | Johann Bodin

Forerunner of the Heralds | Creature | Merfolk Scout | When Forerunner of the Heralds enters the battlefield, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top. Whenever another Merfolk enters the battlefield under your control, put a +1/+1 counter on Forerunner of the Heralds. | Chris Seaman

Hunt the Weak | Sorcery | | Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.) | Mathias Kollros

Jadecraft Artisan | Creature | Merfolk Shaman | When Jadecraft Artisan enters the battlefield, target creature gets +2/+2 until end of turn. | Izzy

Knight of the Stampede | Creature | Human Knight | Dinosaur spells you cast cost {2} less to cast. | Steve Argyle

Path of Discovery | Enchantment | | Whenever a creature enters the battlefield under your control, it explores. (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 the creature, then put the card back or put it into your graveyard.) | Howard Lyon

World Shaper | Creature | Merfolk Shaman | Whenever World Shaper attacks, you may mill three cards. When World Shaper dies, return all land cards from your graveyard to the battlefield tapped. | Raymond Swanland

Huatli, Radiant Champion | Legendary Planeswalker | Huatli | +1: Put a loyalty counter on Huatli, Radiant Champion for each creature you control. −1: Target creature gets +X/+X until end of turn, where X is the number of creatures you control. −8: You get an emblem with "Whenever a creature enters the battlefield under your control, you may draw a card." | Chris Rahn

Raging Regisaur | Creature | Dinosaur | Whenever Raging Regisaur attacks, it deals 1 damage to any target. | Bayard Wu