Minecraft wiki entry for Defeating_the_wither, associated text: Tunnel down to where stone starts to give way to deepslate, tunnel at least 20 blocks from where you land and carve out a 6*6*6 chamber, here you will spawn the wither. Build the soulsand structure and place two of the skulls. Turn the difficulty to "Easy". Then place the last skull, when the wither is charging, run back to the end of the tunnel, if you cannot get far enough, use the shield to lessen the damage. After it explodes, move towards the wither until you see its tail. Shoot at the wither's tail with your bow as you maintain careful distance, move back in the tunnel if you can. When it has half health, charge at it with your sword and strafe hit so the skulls will not hit you. When the wither's last damage point is depleted, it will explode after several seconds. Move back into your tunnel to avoid this, possibly using your shield if you are too close. Gather the nether star and return above ground.