Warp prism warp-in only!

Players are only allowed to attack by sending warp prisms and warping units directly into opponents' bases. No drops, no sneaky pylons, no frontal assaults.

Some possible outcomes includes players (1) being very sneaky, (2) playing mind games with warp prisms, (3) building TONS of warp gates so as to warp be able to warp in a competitively-sized army in very few waves, or (4)  keeping track of the opponents' army units and only warping stuff in when those units aren't around.