Instructions
Load the ̶0;Halo 3: ODST Multiplayer̶1; game disc in your Xbox 360 console and select ̶0;Online.̶1; Select the ̶0;Firefight̶1; game mode from the mode selection screen.
Choose the ̶0;Alpha Site̶1; map and then select ̶0;Heroic̶1; as your difficultly level. Select the ̶0;Invite̶1; button to invite three friends to join your match.
Start the match and instruct two of your teammates to position themselves in front of the two doorways. This will create a bottleneck that the Covenant will have to pass through to get to you. Tell one of them to use their plasma rifle on the Brutes̵7; shields and tell the other to shoot for the head.
Instruct your other teammate to grab the Fuel Rod Cannon and use it only on the Chieftans and Hunters. Tell him to stay out of the middle of the room and you do the same.
Alternate between the doorways and have your teammate with the Fuel Rod Cannon do the same. Resupply your weapons between rounds and reload your ammo whenever there is a break in the action. With this technique, you should pass the fourth set right around the two- hour mark. As soon as the fourth set passes, all four of you will be notified that you earned the ̶0;Endure̶1; achievement.