give kogmaw some tenacity or something!!!
getting stunned as vayne or ashe is one thing; they have an option to escape via stuns/displacements or gap close/anti gap close (vayne tumble or ashe AA, E). being stunned as kog'maw feels like an eternity and you know that once you get stunned or snared or whatever that there is no means of escape. at least increase his tenacity (NOT MOVE SPEED)