https://sentinelswiki.com/index.php?title=Lifeline#tab=Comic_Books:_Lifeline

Tarogath watched as the last of his people were wiped from existence. Jansa Vi Dero, the Terminarch, had offered Tarogath the chance to preserve the memory of his race, the Procitors, and he had taken it. But that meant he would be the last of his kind. He suffered the awful fate of knowing he was the last Procitor.

That was over 700 years ago.

Now, from his eternal home in the Enclave of the Endlings, Tarogath watches the galaxy. Most of the Endlings were content to distract themselves with their new life in the Enclave, but Tarogath cared not for their company. He spent his time, absorbed in observing the rest of the galaxy. He wept for the Mubbloxians and the Piunites as Grand Warlord Voss destroyed their civilizations, unsurprised when Jansa added one from each of their ranks to the roster of the Endlings. But then, he saw something horrible and familiar. He watched as cosmic events circled around a distant star-system in the Milky Way galaxy. The cosmic concurrences there could not be random. He was witnessing the beginning of another extinction event! And perhaps, just perhaps, he could be in time to stop it!

Stealing tech from many lost races and a ship from the Enclave, Tarogath made his way to the planet Earth. There, he brought his wisdom of centuries, his mourning for so many lost races, and his fury against the capricious forces which would bring about such catastrophes. Then, he became the embodiment of destruction. He knew that destroying enough of this foreign planet and killing enough of its inhabitants would slow if not stop entirely the cosmic events which threatened their very existence. With a heavy heart, Tarogath took the mantle of Deadline and sought to leave a scar which humanity may never fully recover from.

He will bring peace to the Earth… by plunging it into the dark ages

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"I have never shied away from the costs of my actions, but now I must prevent my own greatest failure."