After you have saved, kill the group of Raiders ahead then move a little further to find a group of Infiltrators accompanied by a Huntress. They are relatively weak without augments but their ability to cast four buffs at the start of battle makes them stronger than many of their allies. Due to the time it takes to kill them, you should focus on removing weaker enemies first.
Follow the marker right and pick up the Lifesaber (weapon for Lightning that improves the potency of Raise) just in the corner then take out the next lot of enemies. Turn left and ready yourself for a Viking fight. Vikings on their own are not much of a threat since they are vulnerable to the Launch ability; quick Stagger will render them toothless and the battle over. Though they are susceptible to some status ailments, it is not necessary to debuff them first; just push for the Stagger.
Run forward, retrieve the Ember Ring from the Sphere then turn to face the PSICOM soldiers. When dealing with the pair of Huntresses and Raiders, use Diversity until you have whittled the numbers down then use Relentless Assault to mop up. Follow the corridor all the way round, killing enemies in your way, until you reach the two Huntresses and a Viking. It is prudent to kill the female contingent first then deal with the robot last. Finally, pick up the Pandoran Spear (weapon for Fang which improves the effectiveness of debuffs) and head through the door.