My favourite thing is too stick 20 Shoota Boyz (max out with 4*Big Shootas(One belongs to the nob)), in a battlewagon, give bolt on Big Shootas as many as like, Zzap, 2* twin-linked Rokkit Launcher. Move it every turn 6" fire with one of the Wagons weapons but open up with the big shootas and shootas, if you have 5 bolt on big shootas + 4 from the squad thats 27 Str5 AP5 rounds flying 36". Deadly.