Attican Traverse: The Rachni
Unlockable Weapons and Equipment:
Ariake Technologies Shoulder Guard
Krogan message - Citadel: Krogan's Dying Message
Pistol High Caliber Barrel
SMG High Caliber Barrel
Shotgun Shredder Mod
Shotgun Spare Ammo
Pistol Piercing Mod
Check the living quarters beside you to find the M-3000 Claymore, Pistol High Caliber Barrel and Spare Parts (credits). Continue forth to the scout camp ahead and enter the first room to find an SMG High Caliber Barrel and a work bench. There is also some spare parts you can salvage outside for credits.
Continue along the path until you find a dead body. Grab the M-451 Firestorm from him. Use it to clear out the webbing in the tunnel. Continue inside. Destroy the spore pods from a distance since they'll explode if you get near. Continue clearing your way until you reach a large cavern. Kill all enemies there.
Once clear, check out the left side of the cavern to find a Shotgun Shredder Mod beside a dead krogan. Continue ahead and clear the path of webbings and spore pods. Continue until you reached a barrier. Destroy the barrier node then clear the webbing to trigger a scene.
Clear your path and move forth. Clear the webbing to your left to find some reaper tech. Continue ahead until you reach a larger room with more pods. There's a corpse to the left which you can examine. You'll have to deliver his message to Ereba in Citadel later on.
Continue to the next hall and clear all enemies. Move along and pick up the Shotgun Spare Ammo upgrade on the ground before the ramp. Grab the Firestorm to make it easier for you to clear the pods out of the way.
After jumping to the other side, continue clearing the path then grab the Ariake Technologies Shoulder Pad from a corpse along the way.
Continue following the path until you spot Grunt and his men. Clear the path again until you reach the switch. There's also a Firestorm, Med-Gel and Pistol Piercing Mod nearby.
Destroy the barrier and continue forth. Examine the narrow passage. After the scene, you'll be trapped. Look up and destroy the barrier node to lower the lower the barrier to the left. Destroy the enemies there, move in and destroy another node to lower the other barrier. Continue ahead and destroy the last node and kill the last batch of enemies and watch the next scene. Here you'll have the option let the rachni queen to die or help her escape.