Blocks have an X, Y and Z scale. When the block setting 'scaled uniformly' is turned on the X,Y and Z scale will stay equal. When it's turned of the scales can have different values. With Deform Random' you can apply random X, Y and Z values to blocks. The 'Deform Random' command helps you to apply random scales to the block. When you only enable the X direction the blocks will become wider or narrower. When you use the Y direction the blocks will become taller or shorter. If you use the min and max method the command will pick a value between the minimum and maximum you set. You can also decide to create a list of values. In that case the command will randomly pick a value from a list you made. When you selected blocks which are scaled uniformly you can let the command do two things. It can skip this blocks it can turn of the uniformly scaled setting and deform the block anyway.