Team Possession is the second new game mode in which you score by holding the flag. This achievement does not track time cumulatively so must be done in a single match. Legitimately this is incredibly hard without a good team. For the best chance at surviving equip perks that improve your maneuverability and sprint endurance. The flag can also be equipped as a one-shot melee weapon in case you do run into enemies, but the best advice is to try and keep moving. Camping out in a hiding place will not work in this mode, as the flag carrier becomes a beacon and appears on every enemies map. To pick up the flag hold down and use to melee.