In the lead-up to this week’s launch of Hearthstone’s new Journey to Un’Goro expansion, Blizzard Entertainment ran a limited-time promotion that rewarded players with unique prizes for each day they logged in. April 5’s prize was a free Un’Goro card called the Volcanosaur.
Source: Kotaku – Hearthstone’s Volcanosaur Launches Early, Causes 24 Hours of Mayhem