Gears of War 3 Game Guide

Act Three: Chapter 2 – Rescue

The wall team has sniper rifles and oneshots and are in the least peril. The
rescue team will be in the thick of things; on co-op, whatever the first
player chooses, the second player will do the other. As the battle starts you
will both mow down a few small threats while the truck is moving. After the
scene, kill the Grenadiers and the ground guy should mark (click the LS while
aiming) the Digger for the wall team. When these enemies are dead, turn around
for more Drones before a Lambent stalk drops a Drudge. The oneshot can destroy
the all but the slithering head of a Drudge, and don't forget to hit the pods.

Grab ammo at the corner and two more stalks will drop Lambent onto the ground
team, but the wall team will also have a few Lambent Drones to take out. The
wall team should take out the Drudges and then follow the wall path to the
other end and prepare to take out the Drones on the ground at the other end. 
When the ground team moves up, a scene will usher in the Lambent Berserker.
Roll away from the car and then run down the path. Toss frags and quickly trade
fire with the Drones at the corner, but just try to dash to the right and into
the gate before the big girl and the Hammer of Dawn take you out. If you have
to be downed and revived to reach the gate, that is fine. Whatever works.

Before you engage her in the yard, go to the upper right corner and find a 
COG tag on the ground. Then keep your distance and run to the back area and
you will find a note among some ammo behind a the circular building. On the 
lower difficulties you can hold your ground and gun down her chest as she
charges you and she will stun with damage. On higher difficulties she will
not be stunned if you hold your ground so you will always have to roll away.
Try to make her hit a wall, but it's more important to ensure you can roll to
one side and not get stuck on something.

Eventually she will start to leak imulsion, so try to avoid this as you resume
your attack. After a time she will leak imulsion that leaves a strong vapor,
which reduces visibility and is very deadly to the touch. It's always best to
be near someone who can revive, because if she runs over you while downed it
will be game over. Just try to keep a clean spot of ground to roll to and 
always hit the exposed chest when you can. Also, she sometimes leaps forward,
so be ready for a quick dodge or just keep a lot of distance between you two.