If you pull more than 2 doing this quest, you really need to learn to pay attention. The only mobs that are connected are the gate guards, and there are only 2 of them that are together. Ever.

Learn to pull. Watch for wandering mobs. The ones outside of the compound are easy to pick off. Grab a guard while the inner mobs are far away, pull back, and kill the 2 guards. Go back and take out the wanderers on the inside.

There is no reason to ever have to go inside the compound if you've got ranged attacks. Every mob can be lurred out. If you have to get up close and personal to a mob, do it, then run back out, and kill them where you can be safe.

And yes, that red shield hurts, but all you have to do is stop meleeing with the mob and you won't be hurt. Ranged damage and DoTs won't do blowback damage to you while the shield is up.

A tip for hunters and locks: The Follow command is a wonderful thing. If you're dealing with a mob that doesn't have long-range attacks, send in the pet, let them pick up aggro, then tell them to Follow. Once they're back to a safe spot, tell them to attack again. It'll save you from dying at the hands of unwanted pulls.