In Minecraft PE has no shortage of enemies, capable of an upset. And most of the time the player spends in listening, there are no nearby hostile mobs. However, the developers at Mojang did for experienced players the ability to spawn the mob of Wither health 300 units. And that the players risked not in vain, made the drop with him in the form of "Stars of the Lower world" are extremely rare and very tempting for the creators of the pyramids and the lighthouse.
To cause the Wither, you first need to get three head skeleton-wither. This is probably the most difficult task in preparation for spawn of Wither, as the loss of the head of this skeleton is a rare drop and have to kill dozens of mobs to get three future heads of Wither. Then you need to find four parts of sand shower that is easier.
It looks so:
For call of Wither need to put a sand shower in the shape of the letter "T" one block at the base and three above it. Then these three units to establish face to all heads of Wither. If successful, the call will be heard specific sound, and at the top of the screen will scale with the health of Wither. All that now remains only to join the battle.