Panel over, all the info and some thoughts below.
The new Hearthstone expansion, some details of which were already reported, has been revealed as Gnomes vs. Goblins in the Blizzcon 2014 opening ceremony. It contains 120 new cards, increasing the current pool by about 25%. The focus is on the explosive developments of the Warcraft universe’s two diminuitive races, introducing Mechs as a creature type and with a focus on more random effects. Battle.net’s got the details including some new card previews and the announcement trailer is below.