In tournament play, it isn't "banned" in a sense that you are fouled or disqualified for doing it. It's a map design and racial balance issue, which tournaments

In tournament play, it isn't "banned" in a sense that you are fouled or disqualified for doing it. It's a map design and racial balance issue, which tournaments usually solve systematically by placing a neutral supply depot to prevent placing a 3rd blocking pylon. Check out [1] or [2] or search for "neutral supply depot" to find some more information. [1] http://gaming.stackexchange.com/questions/51630/why-are-there-neutral-supply-depots-in-some-starcraft-2-maps http://gaming.stackexchange.com/questions/51630/why-are-ther... [2] http://wiki.teamliquid.net/starcraft2/Buildings#Neutral_buildings http://wiki.teamliquid.net/starcraft2/Buildings#Neutral_buil...