In the same arc, Milim a top tier, ultimate move is stated to be a supernova.
What are we gonna say, the supernova isn't a supernova, this supernova actually contains enough energy to destroy multiple galaxies, yea i think you are stretching at that point, not to mention again Yuuki needing a long amount of time to destroy the universe, despite supposedly already being multi-galaxy level.
So i would be opposed to any upgrade to 3-B, anyway going back to reading LN's.
There are a estimated 200 billion galaxies in the universe and 2 trillion known galaxies.. Also the text in chapter 248 states: "Judging by this, yuuki must have not been able to destroy the world itself. I speculate that after destroying all the stars as a space-time continuum, his lifespan had ended."
Couple things to note from here, Yuuki had already become a "god", something that exceeds spiritual beings(stated in chapter 247), meaning that he already is immortal physically so something/someone must have killed him. He had been able to destroy all the galaxies in the universe but we don't know how long that took, if it took one attack, how long it took for him to die after destroying the every star in the universe, etc. We don't get any info at all, but we can infer some things.
In chapter 247, at the end, it seems like Yuuki didn't have the energy needed to destroy the world so he planned for the others to use their strongest attacks in order for him to devour it with Beelzebub to make it into his and use that energy to enact his plan. The attack gave Yuuki the energy needed to destroy every star in the space-time continuum so it can be confirmed to be universal(through energy).
In chapter 248, it is again confirmed to be able to destroy the "world" and that it was their "greatest attack", with knowing how Milim is already large star level, and with her ultimate skill she can supposedly create a "supernova", added with the others ultimate attacks(adult ramiris, guy crimson, velgrynd, Chloe, Diablo, etc), I think we can confirm it can't be planet level. (honestly don't know why I added this when Yuuki confirmed it to be universal, as it gave Yuuki the energy need to destroy the universe). To add further proof, every statement says it was a universal crisis. Chapter 248, Yuuki destroyed every star in the space-time continuum(and further statements from Ciel), chapter 249 Rimuru says that a "universal crisis had just passed" after defeating Yuuki. Knowing how the combined attack was the reason that Yuuki gained enough energy to destroy the universe, it should be confirmed as a universal attack.
Beelzebub may be able to devour the energy and give the owner control over the energy, but it can't make use of the energy itself. Beelzebub is like the mobius system, explained in the afterstories to be a negative energy system, negative energy sucks in/devours energy but can't do anything other than that, you can't use beelzebub to create a big energy attack(though beelzebub might be able to devour the universe like the mobius system, eating all the positive energy so reversing the universe into it's baby state). he probably use milim's ultimate skill to turn that energy into power, or used some other skill.
I too don't think it's possible for Diablo's strongest attack to be multi-galaxy, and the contributions to the attack is definitely not equal, so I suggest giving the god tiers "possibly multi-galaxy".
ps: Her dragonova is a supernova true, but this isn't her strongest attack. She can creates dragonova through gravity magic(stardust actually) but knowing how she can create a supernova through stardust and that she can use her ultimate skill, with breeder, and stardust to create a even stronger attack, yeah I think her strongest attack would be stronger than a supernova.
Now I'll be gone for a long time, trying to find a way to connect my new printer with this computer and this computer seems to not like like printer
