The Lost Caverns of Ixalan

Deepfathom Echo | Creature | Merfolk Spirit | At the beginning of combat on your turn, Deepfathom Echo explores. Then you may have it become a copy of another creature you control until end of turn. (To have this creature explore, 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.) | Matt Stewart

Nicanzil, Current Conductor | Legendary Creature | Merfolk Scout | Whenever a creature you control explores a land card, you may put a land card from your hand onto the battlefield tapped. Whenever a creature you control explores a nonland card, put a +1/+1 counter on Nicanzil, Current Conductor. | Fariba Khamseh