Minecraft wiki entry for Defeating_the_wither, associated text: You can fight in any of the dimensions in the game. Since there are only three, the choice is not very difficult. However, the most ideal dimension to fight in is the Overworld, because the Nether and the End are very dangerous places. The Overworld has many different environments, so there are many different possible battle sites. However, the Nether is mostly made of lava and rocky cliffs, so it is possible to die in lava, and all of your gear would burn up. The End is most like outer space, so it is possible to die in the void, and all of your equipment would disappear. Not only that, if the wither dies above lava or in the void, you would also lose the nether star that it drops. This means that the Overworld is probably the best place to fight the wither. However, the End has no lack of endermen, who the wither will anger, allowing you to kill it more quickly from half health. In addition, you can "jam" the wither under the bedrock portal, which would neutralize its maneuverability. If you do choose the end, make sure to battle on a large island so you don't fall off. This method of "Jamming" the Wither under bedrock can also be performed using the ceiling of the Nether, making the Nether a feasible place to fight the Wither for players who haven't yet killed the Ender Dragon. (Jamming doesn't work on Bedrock Edition, so beware.)