Rudy's health looks like it's worsening, we only have one option to save him. We need to continue the weird route and level up Noelle's magic enough that heal prayer gets replaced with a new, more powerful healing spell that can fully heal rudy and maybe even revive berdly. Then, after saving Rudy, we need to recruit as one of our party members. This triggers a team-up bonus with asgore (he became a party member at the end of chapter 5) making them both incredibly strong. They're both already considered the most powerful party members you can get in the deltarune end-game thanks to their age so the team-up bonus allows them to exceed the max damage/magic cap that effects susie and noelle. This is the only way to get our party strong enough to beat the final boss of deltarune and break the prophecy