Suffering from a terminal illness and fearing death the man who would become Doctor Yesterday created an armor able to manipulate chronal energy. Discovering that he was unable to return to a time when he was healthy Yesterday decided he would bring all time to a halt by destroying the universe.
Going to the Museum of Natural History in order to focus his powers, he was confronted by Slapstick and Mike Peterson, who where there at the time. In the ensuing conflict the rest of the New Warriors arrived so Yesterday brought to life a Tyrannosaurus Rex skeleton to aid him. Leaving the heroes to fight the T-Rex Doctor Yesterday left for the city surrounding himself with various warriors from the past. Rage and Speedball catch up to him, but he is able to freeze them in time.
However, he then confronted by Turbo and Impossible Man, who asks why Yesterday feared death so much. Yesterday responds that he had wasted his life; never experiencing true love or any real accomplishments. Meanwhile Rage and Speedball broke free from the time trap and Speedball. thrown by Rage, attacked Yesterday. The combination of Speedball`s kinetic energy and Doctor Yesterday`s Armor revealed that he would live for a very long time. Realizing it was possible to go into the future to look for a cure Doctor Yesterday returned everything to normal and traveled forward in time as Speedball had suggested.
By using his armor Doctor Yesterday was able to manipulate ambient chronal energies allowing him to open portals to the past and future, switch people with their past selves, and freeze people in time.