There needs to be a particle beam heavy exotic. Remember the particle beams? Mass Effect had one, and maybe Halo did, too. You charge it up and unleash a straight laser beam of intense, ultra-powerful and rapid energy in a continuous flow until either ammo is depleted or the cool down takes effect. The one from Mass Effect was called the Collector Particle Beam. It would obliterate big and tough enemies but strictly limited ammo. Destiny needs this weapon as a heavy. More specifically, and exotic heavy.