New mechanics include the Inspire keyword, which triggers every time you use your Hero ability, and the Jousting mechanic, which compares card costs to see if you get a bigger minion with more abilities. Players can also retain rank bonuses even if they have a bit of a losing streak and will have a chance to win any of the currently available card packs when a new pack is awarded. So the expansion’s name might sound a bit more like an event, but you could argue that the expansion is plenty eventful by itself.
Source: Official Site