Call of Duty

UPDATE 17^th NOV - The boss now loses it’s purple spots and will require your team to manuever.

'MW3 - One Against All' is awarded for completing the final mission of Act 3 with 6 players. You can either unlock the mission through natural progression or play with someone that has gotten to that point themself.

How to Matchmake with 6 players
It is possible to search as 2 groups of 3 and meet each other by turning off crossplay in settings on your xbox account. To get there go settings - account - privacy & online safety - xbox privacy - view details & customise - communication & multiplayer - "You can join cross-network play" to block. When you load back into the game you can just press on the password screen. To check if both groups make it into the same lobby before the game loads in, press and to 'channels'. It will change from 'party' to 'lobby' and you can now see your friends' gamertags. Back out if needed. Credit to Sunnshhine for the matchmaking info!

Notes
- Pack-a-punch III and going into the red zone isn't neccessary.
- The chopper for the mission will only take whoever is onboard! (Unlike pre-patch where it would drag the squad with you). Making this significantly harder to do with randoms.

Set-up Strategy
- Everyone equip their best gear, although you will have plenty of time to acquire everything you need if you don't have anything.
- Load in and meet up with the other squad of 3 (Now is a perfect time to get the revive achievement if you still need it).
- Invite them to your team by holding + .
- In the low threat zone, complete the 2 contracts 'Eliminate the bounty' and 'Spore control' until everyone has enough for pack-a-punch I (5,000). Share the cash out if needed.
- In the medium threat zone, complete the 2 contracts 'Eliminate the bounty' and 'Spore control' until everyone has enough for pack-a-punch II (10,000), 3-plate heavy armor (10,000), 2x self-revive (2x 5,000) & as many armor plates (150) as you can carry. Share the cash out if needed.
- Everyone head to the mission 'Defeat Zakharov', making sure everyone gets onto the chopper.

Mission Strategy
- Approach the first objective, being careful not to go over mines or push too far ahead too soon - the zombies spawn in waves.
- Get to the building clearing out all mercs inside and keeping an eye out for snipers on the upper catwalks.
- After planting the explosive by holding , leave the building to the west and have everyone push up to the final area.
- As you arrive blow up both helicopters and have everyone replenish their ammo.
THIS IS THE START OF THE ORCUS BOSS FIGHT
- Have everyone stand on the edge of the arena to the north by the ammo, with one person holding to 'power the neurolizer'.
- A helicopter will spawn. Destroy it and Orcus should spawn. As long as everyone keeps their distance from Orcus, you should have a very managable boss fight. He will do a close-range slam attack, medium-range laser attack and also bury himself to subsequently redeploy. Aim for the purple spots and be ready for little purple orbs once his health is getting low. You may need to manuever your team to get a better view of the purple spots as they dissapear (new update 17th NOV).

If a text guide isn't for you, I also have made a full-playthrough video below. Good luck and I hope this helps.

Orcus is the boss of the last mission in Act 3. You will need to complete all previous missions to unlock it, or you can join a squad that is currently performing that mission. We need six men, which means we need at least two teams. You can wait at the mission location to see if you can join the squad that is on a mission and hope for good luck

Got it done, easy way I found (and a bunch of others found) to get it done is to get two teams of 3 and get into the same lobby, we were all playing pretty much from different areas of the world ( I was from Australia, someone was from Brazil, china, Germany) if your case is like mine and you have two people from a similar region get them to host, we had to people from Germany (one in each team of 3) but for some reason even though they were host it would not put us together and just put in the same lobby over and over again, for some reason when I (from Australia) hosted and someone else (from china) hosted we pretty much got placed in a lobby together almost instantly which is probably due to the lack of lobbies in Australia, New Zealand, china etc. btw if playing with people across the globe be ready to deal with ping ( I had 300ms)