He and three subordinates, Telbrus, Darsiris, and Zoraya, were sent to an asteroid field in a dying star system by Executor Selendis; their goal was to find a vault where a colossus was safely hidden. They used a Dark Templar starship of unfamiliar type, and ran into a number of zerg. After a short battle, they landed on the target asteroid and proceeded to the vault. On the way, Aldrion had to deal with the emotional state of his second-in-command, the fellow templar Telbrus, who blamed the Dark Templar for keeping him from defending his brethren on Aiur.
In the end, Aldrion was able to convince Telbrus that the alliance with the Dark Templar was their only chance of survival, and that the colossi were a dangerous weapon that could turn out to be more dangerous than the foe it was used against. Shortly after this, Aldrion sacrificed himself in order to allow the rest of his team to save themselves and the recovered colossus from the approaching zerg.