'Warzone' is the eighth and final level and is made up of 6 events:
1. "Time Bomb" - Time Attack
2. "Tanks For The memories"
3. "Minded Games" - Survivor
4. "Bombed Out" - Run the gauntlet
5. "Warlord" - Siege
6. "Wargames" - Sprint
GENERAL TIPS: Considering you don't have to get a certain score or even win the tournaments, if the levels are not timed, take it slow and take enemies out from a distance if possible. If they are timed, shoot while running and if you miss killing someone, just keep going. Make good use of your "snap" move by pressing to do a quick 180 turn. It takes a while to turn around simply using the thumbstick and you'll most likely get yourself killed that way.
Also, don't bother trying to get skullshots when playing through on Insane. Do all the tournaments on Insane and enjoy the game, then go back in Single Event mode on Casual to find the skullshots and do all the miscelanous achievements.