Minecraft: Edition

This achievement can be boosted with a 2nd controller, or with a friend. Whenever the game has started, no one can join in the current round. So simply set up a public battle match. Immediately ready up by pressing . Then when the match starts, wait for the countdown to finish and immediately either suicide or kill the 2nd player. Repeat for another match and then ready up again for a 3rd match. Hopefully no one has joined in when the 3rd match starts, and you can get your achievement.

- If players join while you are ingame, select their name and start a vote to kick them. If you keep kicking players with both of your accounts before a 2nd random has joined, you can keep the lobby to yourself.
-It HAS to be a public match (either casual or competetive)
-It HAS to be 3 consecutive matches in the same lobby. Doing 1 win, then backing out and doing 2 more wins in this way does not count.

Alternatively if you cant do 3 consecutive wins without anyone joining, you can lock down a lobby with 8 accounts/controllers. (guest accounts work)

Easy with a second controller

Open the Mini Games menu and create a battle mini game. Make sure to tick the box next to public. Make sure the map Crucible is selected.

Log in with second profile on a second controller before entering the lobby world. Once the lobby world has loaded quickly hit then select the map Crucible. Quickly hit to begin the match before anyone else can join.

Once the match has begun use your second profile (the one you don't want the achievement on) to run into the lava and die. Repeat this 3 times to get the '...Has Become The Master' achievement

You can't exit out of the lobby and back in and have it count it HAS to be three games in the same lobby.

You do not need to do this with other players online, you can simply join with a second controller and start the round with before anyone else joins.

Here's a video: