This is the Explore Un’Goro HS Warrior Card from the Journey to Un’Goro expansion due for release in April.
It’s a Warrior class spell and the card reads: Replace your deck with copies of “Discover a card”.
You can get Explore Un’Goro by opening packs from the Journey to Un’Goro set.
*A fun card for some Meme decks, or a pickup in other discover mechanics late game.