Op, there is no such thing as a spragga build. The idiots who told you that are immature 8 year olds that are using mommy's IPhone without permission.
Well first you have to sell your castle and leave that spot open. Next, build spy towers in a cirle around that open plot. Then, build factories at all four corners. Next, at midnight, draw a pentagram in the open slot and sacrifice 10,000 soldiers to the Warbeast. As you sacrifice them, chant "Oh Mighty Spragga, Bless me With your Build! " Next, Buy 3 Horns and blow them at the same time. Then wait. If successful, you will have his legendary build the next day. Good luck.