Details for the last StarCraft 2 installment, Legacy of the Void, have been few and far between since BlizzCon last year. To help alleviate that, Blizzard did something it usually doesn't do: Attend E3 to pass out some much needed info to its fans.

On the first day of the show, it was announced that Blizzard would release three free prologue missions to people that pre-purchase the game. Everyone will eventually get to play them for free, but pre-purchasers will get first crack at the Whispers of Oblivion missions, which are designed to bridge the story gap from Kerrigan's defeat of Arcturus Mengsk in Heart of the Swarm to the beginning of the Protoss campaign in Legacy of the Void. We got some more details about the missions and even got a bit of hands-on time behind closed doors at the show.

With the Swarm now in pursuit of the fallen Xel'naga Amon and his malevolent alien hybrids, the Protoss have realized that retaking their homeworld of Aiur is possible, said Jason Huck, lead designer of StarCraft 2. The goal of the prologue missions was to reacquaint the players with Protoss, as well as show Zeratul's continued pursuit in tracking down the prophecies that will locate Amon. All the missions will be from Zeratul's perspective, with players controlling a small base and building units in the first two, and then using Zeratul himself as a hero unit in the third.

The first mission, entitled Dark Whispers, Zeratul has shown up at a planet where he expects to find part of the prophecy that will allow him to stop Amon and the Apocolypse. What he finds in a Terran Moebius base that has been experimenting on Protoss Templars. Kerrigan and the Swarm are there to destroy the base, but Zeratul's forces must save the captured Templars. The mission has you dodging Zerg forces while killing Terrans. You can build any of the units you could build in multiplayer, but the mission is timed so late game units are pretty much out of the question as you rush to free the Templars before the Zerg level everything. It was a fairly simple mission and will serve to get players familiar with the Protoss units and playstyle, particularly if they have not played them in multiplayer.

The second mission, Ghosts in the Fog, has Zeratul's forces attacking an ancient Xel'Naga temple on Atrius that is defended by Tal'darim forces loyal to Amon. While this is another straightforward mission of building units and destroying the enemy, the catch here is that there is limited vespene resources on the planet. Instead of building collectors to get a routine influx of the gas, you need to wait for vespene eruptions on the planet to collect a limited amount by having your units walk over them. It forces you to be a bit more strategic in the units you build, knowing you will eventually run out of the resource.

The last mission, Evil Awakens, was kept under wraps for now, but players will play Zeratul in much the same way they did in the Whispers of Doom mission in Wings of Liberty. You will infiltrate the Temple of Erris and take on more Tal'darim to get the final part of the prophecy.

More details on the pre-purchase program will come sometime in July. We're waiting ...