Keeping up with my current train of thought why not create a gun "vortex gun"?
Drawing from the Magnus lines this would be an Elemental/fire damage 5star gun.
The regular bullets would be fast and have a chance to deal moderate Fire to their target.
The charge attack would be very different from the current Magnus line charge attacks.
Instead of a fast hard hitting bullet with high flinch chance, this gun would fire a slow fiery orb, enemies nearby would be pulled towards the bullet and while it traveled it would deal numerous hits each with a chance to inflict Strong Fire (invinciticks included to balance the gun). When the bullet dissipates it would fling the enemies away but not as much as a 5star vortex.
The charge bullet would have the appearance of a combination of Pulsar charge and a Fire Whirl.
This gun could be used to collect and send enemies to a waiting bomber or brandish charge, it could be used to pull monsters away from the team or to just reposition them entirely.
I still think that invincitrinks are a bad way to balance something. less damage, less chance for proc, and you still have your knockback.
the overall idea is ok, maybe the vortex effect could activate after a while, like pulsar line normal bullets, so that enemies don't get sucked towards you.