Just as E3 was ending last week, Major League Gaming's Spring championships were getting underway in Anaheim, California. Blizzard held a press preview during the opening hours of the tournament to show off the new units and features coming to Starcraft 2's multiplayer component in the upcoming Heart of the Swarm expansion.

Each of the three races in the game has a few new units and abilities to study (which you can see in the included trailer), and hardcore players will no doubt be combing through them as the expansion goes into beta. But Heart of the Swarm's multiplayer represents an interesting change in Blizzard's original plan for the three-part series that is Starcraft 2.

As lead producer Chris Sigaty (who doubles, by the way, as the lead guitarist for Blizzard's in-house metal band L80ETC) tells Joystiq, the new units are all about adding something to the game without removing what's there.