So, in the many versions of the Dragon Ball series, we've seen many different transformations. For example, in the Dragon Ball Heroes franchise, Broly, and I'm talking about Z's version of Broly, the one driven mad over his hatred of Goku, has achieved both Super Saiyan 3 and Super Saiyan 4, both of which are in combination with his normal Legendary Super Saiyan transformation. I've seen plenty of fan work that combines Super Saiyan Blue with Super Saiyan 4, but I'm wondering about something. Super's version of Broly is a pure-hearted Saiyan, meaning he could take part in the Super Saiyan God ritual, and with enough training, he'd also be able to achieve Blue. Now in the manga, Goku is able to master Super Saiyan Blue, allowing him to perform the signature technique among the Gods of Destruction, the Hakai. And in the Tournament of Power, Vegeta unlocks a variation of Blue that's on par with Goku's Super Saiyan Blue Kaio-Ken x20, if not Mastered Ultra Instinct. And even further into Super Dragon Ball Heroes, Vegeta combines the Evil Ki with his Super Saiyan God Super Saiyan (Evolved) transformation. While this makes him much stronger, just like Goku with Mastered Ultra Instinct, it takes a heavy toll on his body, and he quickly loses the transformation before he can even begin to fight Goku Black. Anyway, what if Super's Broly learned how to control the Legendary Super Saiyan like Kale did, and then combine its power with Super Saiyan Blue? What sort of aura and other features do you think the transformation would have?

If Broly combined legendary with blue he would likely have a cyan (light blue) aura, since legendary alone takes a lot of stamina Broly would have to learn to further refine his ki control much like Frieza had to do to control his "Golden Frieza" transformation. He has a lot more stamina than Frieza which is good, but against overpowered opponents that control would help a great deal. The Super version of Broly is already stronger than even most gods of destruction, combining that with blue may possibly put Broly in angel tier in power.

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Would it put him in the same tier as Jiren? Remember, Belmod isn't the most powerful fighter in Universe 11, and while Angels are more powerful than the God of Destruction, they have laws that prevent them from taking sides, which is what caused Merus to be erased from existence, be violated Angel Law, which is the only true was an Angel can die. By that meaning, Angels cannot be measured as the strongest fighter in a universe, as they are more of a guide and attendant than they are a fighter. I know this because of a YouTube series which is a what if Goku was sent to Beerus's planet. Goku trains with Whis for 39 years and replaces Beerus as God of Destruction. Because of Kakarot's reign as Universe 7's God of Destruction, Universe 7 becomes one of the universes that didn't risk erasure in the Tournament of Power. In a video in the series, the Grand Priest sends Kakarot to the other seven universes that participated in the Tournament of Power and give their respective God of Destruction pointers on how to do their jobs better. In Universe 6, he learns more about his Saiyan blood, and in Universe 10, he talks to Zamasu about his philosophy about the gap between Gods and mortals. When he gets to Universe 11, he fights Toppo in his God of Destruction form. The reason for this is because that's about as close Kakarot will get to fighting another God of Destruction, which is forbidden, that's why in the manga, the Gods were surprised that they would be fighting each other, because it had always been against the rules. When Toppo tells Kakarot that Belmod isn't the strongest fighter in Universe 11, Kakarot at first believes he's talking about Marcarita, who he says doesn't count, only to learn about Jiren. I'll post the videos at some point if you want to see them

7521941 I am aware of the law of angels not being allowed to interfere which would make it more difficult to gage the extent of their power. It is heavily implied however that angels are considerably more powerful than gods of destruction, it took super saiyan blue Gogeta to barely even restrain a legendary super saiyan Broly. Brolys power is at least comparable to Jiren, possibly even stronger than that and we know that Jiren is god level. This is Broly as he currently is, even with greater control and simply not even further transformations Brolys power level will get a significant boost. You do raise a good point that we don't know the upper limits of god of destruction levels of power. As you stated yourself Toppo stated that he is indeed stronger than Belmod and we don't know how strong Belmod is compared to his colleagues. Judging by Beerus's performance in that god of destruction battle royale it appears that Beeurs is the strongest god of destruction. If Broly is able to combine legendary and blue together he will be considerably stronger than Jiren. This what if series where Goku was bent to Beerus's sounds really interesting.

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Well, in that battle royal, Belmod told Marcarita that he got knocked out on purpose so he wouldn't have to continue fighting, so the three top tier Gods of Destruction are Beerus, Belmod, and the yellow mouse. The closest thing to fighting another God of Destruction that Beerus has done in the anime is the Arm Wrestling Match