The Glassing of Djangoris Alpha IV

Like I said. Lasgun one shots Forerunner.

And two stage cyclonic torpodoes and teleporting the said torpedoes make Imperium superior enough to destroy Forerunner.

And nothing in Halo travels at relativistic speed save for their actual missiles.

Imperium wins every single naval battle due to insanely superior speed.

Halo gets wiped out by Imperium on the front, and its galaxy torn to shit by Necron celestial orrery.