Once you buy him he’s available on all platforms
Well this is an interesting promotion.
Khadgar is now available in Hearthstone as a Mage Hero character, but there’s some caveats. Up until April 24, players can purchase him for $4.99, at which point all of the proceeds will go to the World Wildlife Fund.
The big catch? You can only buy him on iOS. Once he’s purchased he can be played on all of your accounts, including Android and PC, but he’s exclusive to that storefront. See, I told you it was an interesting proposition! Though this isn’t without precedent — Blizzard also had a Samsung exclusive card back.
Khadgar Comes to the Tavern! [Hearthstone]