Terminus was, by his own account, beaten by Batman at some point in his past and as a result he has some rare condition that required painful treatment to extend his life. He vowed to spend the remainder of his life in pursuit of defeating Batman, and showing the people of Gotham that Batman is the true villain.
Terminus was created by Batman and Robin writer Peter Tomasi and artist Patrick Gleason in 2012.
Major Story Arc
Batman and Robin
Terminus wants to see Batman die and gathers a group of villains who all have a similar interest to raise an army against Batman. He is dying of a sickness and wants to fulfill his plan before his death, keeping himself barely alive by injecting himself with toxins. His army is finally unleashed and hurts Gotham citizens by branding the Bat symbol on their chests. Then all the villains he gathered attack Gotham at large until Batman and his crew fight them back. Terminus then takes a big suit to attack the Batcrew. Batman is almost beaten, but then Terminus' time runs out and he breaks down. With his last breath he tells Batman that he has launched a rocket and says all the attacks were just a diversion. But Batman stops the rocket and Terminus dies with his plan avoided.