In the midst of a furious global superhuman arms race, sparked by the emergence of artificially constructed gods like India's Krishna and Iran's Malak-al-Maut coupled with the unspeakable destruction left in their wake, Dajjal was set loose from an American military base in the Middle East. Originally meant to be used against the Iraqis, and named after Al-Masih ad-Dajjal, an Anti-Christ counterpart from Islamic mythology, his purpose soon changed after Krishna's destruction of Pakistan sent the world spiraling into chaos.
Dajjal described himself as being not insane, but "without sanity" ---- if sanity could be described as the best possible set of reactions to the structure of the perceived world, then the concept of sanity did not apply to him, as Dajjal's perception of the world was unlike any other. "Tactical perception" was the common buzzword the US military attached to Dajjal's powers, but it was a lot more elaborate than that. Humans could only live through time, but Dajjal could perceive every moment of the past, present and all possible futures. All of time was open to him; even as Simon Reddin, the story's narrator, described his nature in the future, Dajjal could hear and comment on Reddin's summation while standing in the past.
It was hypothesized that the Americans had programmed Dajjal to follow those timelines with the most open pathways, as this would avoid near-futures in which he was terminated. However, they forgot that Dajjal perceived the vagaries of time differently, his vision geared to events independent of his own actions. Reddin also added that Dajjal seemed to prefer exploring the possible doomed futures; most likely because of their simplicity, as in these futures there were fewer alternate pathways as humanity grew closer to their extinction. In the middle of Reddin's description of him in the future, Dajjal declared that all possible timelines now twisted towards India, thanks to Krishna's actions, and therefore that was where he would go.
Meanwhile, the artificial gods constructed by the other countries had all walked into Mumbai to kill Krishna, and one by one, Krishna disposed of Perun, Malak and Maitreya, until the only one left standing in front of Krishna was Jerry Craven, an obsolete American super-soldier built in 1974. Jerry looks around at the new India Krishna had constructed, and marvels at how it seems like Heaven. He explains that he has been sent to kill Krishna, but can't, because he doesn't see anything wrong with Krishna's actions. Just then, Dajjal arrives in Mumbai and confronts Krishna and Craven. He declares that he can see all possible futures, and that "all but one are so boring that I cannot bear to live through them". Ripping open the unknown power source in his chest, Dajjal detonates, his suicide killing Krishna and Craven; simultaneously annihilating India, China, Russia, and most of Europe, killing over a billion people in the blast.