Spawning Allows Cross Expansion
Blizzard has released a video detailing a new feature for Starcraft 2. Well, not exactly a new feature, more an old-school one that's making a reappearance. Blizzard calls it Spawning, and essentially it is to Starcraft 2 what CD Swapping was to Starcraft or Warcraft 2, letting players who don't personally own the expansions play with the units and upgrades that Heart of the Swarm (and the upcoming Legacy of the Void) when in a match that includes a player that does. It works for starter edition as well, allowing those who want to play with friends but not wanting to drop the money on a single player they don't need to out-strategize their friends till their hearts content.
The news release from Blizzard sums it up well:
'When a Starter Edition player joins a party with a Wings of Liberty-level player, both are instantly playing Wings of Liberty. When those two players then join a party with a Heart of the Swarm-level player, they all immediately gain access to Heart of the Swarm content, and they keep that access until their party no longer includes any higher-expansion level players.'