You will unlock the Web Line, as part of the story. Hold  to aim at a far surface, press  to fire a Web Line, on which you can walk above your enemies. Then, when you're above them, press  , when it's safe to do so, to web them up or press  to Web Strike them – again when it's safe, meaning no other enemies are looking. Do this to 25 enemies, either in the main story or in side missions, and this trophy will unlock.