Check out the previous missions here:
Mission 1
http://spacehulkmissions.blogspot.com/2010/12/mission-1-breakthrough.html
Mission 2
http://spacehulkmissions.blogspot.com/2010/12/ark-of-dust-mission-ii-surgical.html
Mission 3
http://spacehulkmissions.blogspot.com/2011/01/ark-of-dust-mission-3-scramble.html
Deployment and Forces
Space Marines:
The Space Marine player has one squad consisting of five terminators. The Space Wolf squad consists of a sergeant armed with a Power Axe and Storm Shield, a marine with an Assault Cannon, two armed with Storm Bolters and Power Fists and one armed with a Chainfist and Storm Bolter. The Space Marine player must split his squad in to two teams. One team of two marines must be placed in Room A and one team of three marines must be placed in Room B.
Genestealers:
The Genestealer player begins the mission with one blip. The rest of the blips must be divided in to reinforcement groups. 7 single blip counters and 7 stacks of two blip counters must be laid out at random. The Genestealer may play one of these 14 reinforcement groups per turn (so either one or two blips.) Once he runs out of blips, discard 4 each of the one and three blip counters and form 5 stacks of two blip counters and 4 single counters to form the smaller second wave.
Special Rules:
None.
Victory
Space Marines:
In order to win the mission, the Space Marine must kill all of the Genestealers and have at least one surviving marine at the end of the game.
Genestealers:
The Genestealer player wins if he kills all of the Space Marines before both waves of Genestealers are destroyed.