Rey says [earlier in the movie] that he can’t stop seeing what he did to his father, so anything that instantly establishes that link should work. And it needs to be startling enough to stop Kylo mid-swing, anyways.
Just realized I said our golden ticket right here. Try putting flashes of Kylo killing Han after he raises his lightsaber. Try to replicate the style of the visions we created for the beginning of Ascendant.
You can put the softer “Ben, come home” when he caresses his face before falling.