To accomplish this, you'll need to have purchased the Normandy weapon, armor, and shield upgrades from Garrus, Jacob and Tali respectively; for every upgrade you do not purchase, a squad member will die during the approach to the Collector base. You will also need to assign the right people to the right specialist roles to ensure their and other squad mates survival. Also, every squad member, those in your squad in addition to those holding the Collectors at bay, must be loyal or they will most likely die (it is possible for a squad member who is not loyal to survive, as long as they are not selected to lead the Fire Squad or be in Shepard's team throughout the mission). At the end of the mission, if the "combat strength" of the team left behind to hold the door is limited (for example, so