By the power of truth, I, while living, have conquered the universe.
Kurt holds off the Covenant as he is dying so Halsey, Mendez, Tom, Lucy, Blue Team and the slipspace pods containing Team Katana can go through the antechamber portal into the Micro Dyson Sphere. Kurt detonates the FENRIS warheads and destroys Onyx as the planet surface is torn apart and is revealed to actually trillions of Sentinels which engage the Covenant fleet.
The Dusk plans to make the jump back to UNSC space, the survivors in the Dyson Sphere lament the deaths of Will, Holly, Kurt and Dante then decide to explore the Dyson Sphere and find a way to open the pods.