Minecraft wiki entry for Defeating_the_wither, associated text: To pull this off, go to the Nether and dig up into netherrack until they start seeing bedrock. The player want to be 2 levels down from the first layer that has bedrock blocks (Y level 121). Dig out a 3×3×3 room for the Wither to spawn in, as well as a 1-block wide 2-block high tunnel for them to hide in while waiting for the Wither to grow. A tunnel of about 40 blocks deep should do. Now, spawn the Wither in the 3×3 room, and run into the tunnel until the player is 15 blocks away. After the explosion, it is likely that the Wither will be floating up into the uneven bedrock ceiling. The player should be able to get a vantage point where they can shoot it with arrows until it drops to half health. At this point, it is possible that the Wither may hit the player occasionally with a skull, but ideally it is trying to fire them through bedrock blocks and thus not able to get the player. If they get hit, retreat a little and heal. Most importantly, try to stay on the same level that they started out with, because if they have descent too far, the Wither will do so as well and there will be no more bedrock blocks to block the skulls it fires.