Addon: Withered Storm

To make it Summon just like a Normal Wither but the Soul Sand or Soul Soil in the middle is replaced with a Command Block Like this: 

and the Wither Storm will appear and then You will get the message Achievement Made it

These are some Items, Blocks, and Entities:  

Wither Storm:  

and also added some structures like Abandoned Grandpa's House, Command Of Sword, Formidi Recipe