Old formation, 3 Apsalus, 1 unit with machine gun(WZC or Cgue) on top of tower.
Modern Formation: 4 ap or 3ap + AR psyco, with one ap on top of tower 2 to back shot, cuz machine gun doesn't stuck mobs anymore, they just fly up.
New Way: 3 Ap + Justice. 1 ap get infinite ammo and get on tower 2 as usual, then justice get infinite boost and vulcan to attract mobs. Since ur on infinite boost, they should be able to catch you, but they will follow.
Be awed by my prowess!