Jadelight Spelunker - 196 R LCI

When this creature enters, it explores X times. (To have it 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 that creature, then put the card back or put it into your graveyard.)
The River Heralds found clues to a grand heritage below Ixalan's surface.
rare
Creature — Merfolk Scout
From the Magic: The Gathering set The Lost Caverns of Ixalan.