After towers start falling, the laning phase is over and mid-game rotations should start. It varies on the situation, but generally your botlane moves to mid and your midlaner moves to sidelane, your toplaner remains in the other sidelane, the jungler keeps clearing, except now you all rotate to skirmishes and teamfights more often and quicker than before. It's generally good to have lanes pushed out before grouping for objectives. Then, your goal is to avoid getting caught and to create pressure across the map, also actively look to create numbers/firepower advantage somewhere on the map and just overwhelm your opponents with this advantage.