This achievement must be obtained through multiplayer adversarial, the game type being Team Leader.

How the game works:

If a leader kills another player, that player can no longer respawn. If a leader dies, the entire team can no longer respawn. If a leader gets to the designated extraction point, their team wins. If both leaders are dead, it becomes like a survival match and the last team standing gets the win. To become a leader, you must kill the other leader in the match beforehand and if nobody kills him it is chosen randomly. You get a credit toward the achievement if your team wins while you were the leader.

Getting this achievement without boosting:

Focus on killing the opposing leader, otherwise you will never get a chance to be one. Many people hide at the spawn if they are a leader and sometimes have a bodyguard with them. Therefore, try rushing to the spawn right away and throw grenades in corners in hopes for a kill. When you become the leader, the best action to take is to hide fairly far away from your spawn, ideally looking at the red extraction point to stop the enemy from reaching it. Encourage your team to kill the opposing leader while you hide and then have them finish off everyone else or try to rush to the extraction point if there's only one enemy remaining. Win twenty times while being the leader and you will get the achievement.

Getting this achievement with Boosting:

You will need 6 players, so find 5 other people willing to boost in the achievement trading thread.

Have someone host a player match with a max of 6 players and 5 private slots, doing Team Leader on Kill House. Take turns getting each person the achievement. You may want to split it into two turns per person where they get 10 wins each time so nobody leaves when they are done. Whoever's turn it is must first become the leader, so spend a round having them kill the opposing leader to get started. Then, have each team go to the rooftops or long catwalk on Kill House where the person getting the achievement quickly takes out the opposing team, it should only take 15 seconds. Have the host start the matches right away when they're over and you should get through everybody fairly quickly.