This is the Gentle Megasaur HS Card from the Journey to Un’Goro expansion due for release in April.
It’s a Neutral minion and the card reads: Battlecry: Adapt your Murlocs.
You can get Gentle Megasaur by opening packs from the Journey to Un’Goro set.
*Lots of Murloc synergy in Un’Goro.