Minecraft wiki entry for Defeating_the_wither, associated text: A somewhat more complicated yet very enjoyable variant of this tunnel strategy is to rig the tunnel the player have constructed with TNT. The player could, for instance, build a tunnel as illustrated by the figure above; the idea behind this is that the player can anticipate when the boss will crunch his way to a point sufficiently close to a pair of TNT blocks the player has placed, and if they are accurate, they can have the TNT explode at that very instant, dealing a lot of damage. Be sure not to place the first pair of TNT right next to the room in which the player will spawn the Wither, as the initial explosion would just destroy these. The drawbacks of this strategy are that it can be difficult to tell when to ignite the TNT; if the player is too fast, the TNT will not have the desired effect. If the player is too slow, the wither will simply destroy the TNT prior to its detonation. In addition, the player might need a lot of TNT to completely kill the Wither, and thus they will have to dig out a long tunnel. Therefore, it is strongly advised that the player to use a bow and a sword when the "armor" stage has been reached in the sections of the tunnel where there's no TNT to do the hard work. Also, if the player doesn't have enough TNT, be sure to dig out an extra tunnel as an extension of the TNT-triggered one, so as to finish the wither off with arrows or swords should needs be.