This is the Pyros Elemental HS Mage Card from the Journey to Un’Goro expansion due for release in April.
It’s a Mage class legendary minion and the card reads: Deathrattle: Return this to your hand as a 6/6 that costs (6).
The resurrected 6/6 then reads: Deathrattle: Return this to your hand as a 10/10 that costs (10).
You can get Volcano by opening packs from the Journey to Un’Goro set.
