3 of my close friends and I got Endure at Oni Interior AlphaSite. Two of them died 22 times each. One of them died 9 and I died 10 times so there are plenty of lives to go around. We had about 9 lives at the time it was finished. Conservative can be effective. Sometimes, theres a need for someone to take charge but never kamikaze. I had 360K points myself out of the 600+ we had. I mainly used plasma pistol + automag. It took 2 hours.
Here are some tips: (AlphaSite)
At least 2 out of the 4 people should carry a plasma gun as their secondary. Charged plasma pistol shots completely eliminate Brute armor leaving only the need for one quick headshot to kill.. even after the 2x enemy health skull is activated. At some point, enemy shields will deflect bullets further adding importance to plasma based weapons. USE THEM!
There are two paths from which enemies come from so there should be one person on each side scoping in to headshot grunts. Grunts are one shot kills with the pistol or carbine. Its best to eliminate them first since they can easily kill you with a plasma grenade.
Once the Chieftan shows up, priority on him. If the fuel rod guy comes out first, kill him, take his gun and use it on chieftan. Save the extra rounds for Bonus round assuming its nearby. A successful bonus round means 4 bonus lives + 4 lives for completing the round. This is a great morale/confidence boost.
SMG works beautifully on drones. Automag or Carbine on grunts/unarmored Brutes/jackals.
Prepare yourself for possible lag at the latter stages of your achievement attempt. My last round on the 4th set was nearly unplayable.
Power weapons on the map include Sniper Rifle, Shotgun, and theres a Rocket Launcher nearby where the enemies come from.
COMMUNICATE! Yeah, it takes 2 hours. Yeah, you run out of jokes. Communication is key. From telling your teammate that theres a freaking chieftan right behind him to asking guys if they want to pick up the rocket launcher. These things ease the process.