Hearthstone will receive new Scholomance Academy expansion
Blizzard introduced the next expansion pack for the Hearthstone TCG called "Scholomance Academy". It will be released in early August, and it brings dual-class cards in the game.
The developers already announced 135 new cards and two fresh mechanics. The first one represents new class cards with features of two archetypes at once. You can distinguish the cards by their appearance: it has two colours. There are only ten new combinations:
Druid/Hunter; Hunter/Demon Hunter; Demon Hunter/Warlock; Warlock/Priest; Priest/Paladin; Paladin/Warrior; Warrior/Rogue; Rogue/Mage; Mage/Shaman; Shaman/Druid
Also, Blizzard added the new mechanics of the Spellburst; it's an effect that works once after you cast a spell. You can distinguish cards with this feature by a specific description on them. Hearthstone also will receive new spells from the category of academic disciplines, a Phase 2 of the Year of the Phoenix and much more.
You can find more details in a video from the developers, or on the official website of the project.