Amalgam: Who they were, how they came to be

The Legion. Once a part of me was something like them. He had command of a vast fleet thousands of vessels, the very finest a Galactic Empire could produce. It could shatter entire planets, destroy suns, transit thousands of light years in but a moment. withstand the fury of a Super Nova... It was thought nothing could defeat it. My fleet had, not only the finest ships, but the best of crews, obedient, loyal, yet brilliant. Nothing should have been able to withstand what my fleet, no, my Emperor's Fleet, could unleash. I was proud of my Fleet, and my Emperor was proud of me. Then a Great Power attacked, not just the Empire, but the Throne World. The sundry defenses of that world could withstand much, yet they fell in less than a day. My Emperor summoned me, my fleet, my crews back to the Throne World, and we were there in minutes. The shock of seeing one creature having razed the defenses of the Throne World so quickly was severe, but it did nothing to slow us down. I deployed my ships into a nearly perfect attack formation, and we hit the invader with blow after blow, from weapons of every sort imaginable, all to no available. Within a day, the fleet was destroyed. I was, not merely killed, but consumed, by the creature that called itself Legion. It consumed the Throne World, the Emperor, our entire Galaxy, and within a month, we (for I was no longer 'me', but a part of this creature) had consumed the entirety of our Galaxy, and were looking around, greedily, for more. Finding nothing left, we shifted to another dimension, ravaging and destroying everything we found. So, after having seen the Legion I had became a part of, however small, however fragmentary, destroyed at such tremendous cost,, I was stunned to hear of an attack by "Legion". But these pretenders, were not the host I had been consumed by, nor even lackeys scouting for new meals. This was a mere interplanetary empire, of the sort I had eliminated by deploying a single squadron. Compared to who and what I was, they are  a joke... but compared to what little is left of me, of us, of all that each of us once were, they are dangerous. They are a joke, but I am not even a punchline. But I know they can be defeated, and so they will be. If not by the Amalgam of the residue of thousands of destroyed  Heroes that I am now a part of, then by the efforts of the other Heroes of this world. I failed my Emperor, my Empire, and my Fleet, thorough no fault of my own. I cannot afford another such failure...

The story the Admiral just told is a common one. I, too, when I was a separate being, was guilty of the Sin of Pride, which led to the downfall of countless millions. I was an Angel, of a God I no longer remember, not the Leader, but  one member of a Mighty Host. We were so used to dispatching infernal invasions, it had become routine, and why not? Our routine worked, each of us was better than any ten of them, and we worked together with flawless precision, all praise to our Lord, while they would fight and squabble among themselves! How could we lose? We could lose by underestimating a single foe, believing that he was just any other demon. He had already consumed most of our ancient foes, and added their might to his own, but we did not even bother to check... Why should we? We followed our usual plan of attack, that had worked so well for millenia... but this threat had all the knowledge of all our enemies, in the iron tight control of one mind. who was expecting just that. We did not expect anything of the sort could happen? Why should we? It had never happened before? Instead of fleeing, it attacked all of us... at once... with a bewildering array of powers, from thousands of sources. We were cut down before most of us could attack a single time. I lived long enough to hurl a bolt of lightning at it, but it was much faster than lightning. Then it killed me, consumed my essence, devoured my soul... and I knew nothing for a very long time. Our God sent more angels, I understand, lead them into battle himself, fearlessly, and why should he not? He was no mere angel, but a God, Invincible and Immortal. Except, against such powers, he was neither, and he fell, as well. I remember, faintly, thinking that our 'Legion", this one horrid creature with so many names, so many souls... considered Gods to be a very special treat...

Almost forgot the important part:
The Amazing Amalgam
ID: 10859
Squad: Select Association of Powerful Superbeings