Back 4 Blood

For this achievement you have to win 2 out of 3 rounds of Swarm where you take turns playing as Cleaners/Ridden and win a round by surviving longer as a cleaner than your opponent. This can be boosted in a private 1 vs 1 with a partner or solo if you have game pass and access to a computer and a second connectable controller (Explained Below).

To quickly win, make sure the account getting the achievement fights Ridden to survive about 40 seconds and then allows themselves to die, the account not getting the achievement does not have to actively play. When the main account is on the Ridden team, spawn as a spitter (have to wait 1minute for them to gather before you can spawn) around the corner from the idle cleaner and quickly go and shoot them with RT to kill them quickly(should be quicker than 20seconds).

Now win 1 more Round and the achievement will unlock.

Joining a private 1vs1
1.Launch the game into the Home Fort on both accounts, open the menu with select and choose swarm on both accounts.
2.Select Private server.
3.Boosting partner/2nd account selects Swarm and scrolls down to the bottom for "Join Private Server" and then enters the same code in Caps as shown on the Hosts screen. Once done this will launch you both into a private 1vs1.

Game Pass Xcloud Solo Boosting:
1.Set your console as your HOME XBOX (This allows any profile on that xbox to play your game pass games).
2. Create a second xbox profile and play B4B on that account on the xbox.
3. Go to your computer browser and sign in with your main account on Xcloud and now you can play both profiles at the same time for free to boost solo.