For a time, it was believed that Zor-El thought that Krypton was being devastated by a "phantom plague" and so he genetically altered Kara's biochemistry to enable her to defend herself against such threats. As such, Kara Zor-El developed powers even beyond that of a Kryptonian exposed to yellow solar radiation. It was also thought that Zor-El sent her to Earth to kill her cousin Kal-El, whom he suspected was also infected by this phantom plague. This was later revealed to be false, and was actually Kara's warped perceptions of her father caused by severe Kryptonite poisoning.
In fact, Zor-El was a very noble figure. Having migrated his friends and family to the bottled city of Kandor, Zor-El used technology from leftover Brainiac Probes to bolster the city's defenses. Zor-El along with thousands of Kandorians was eventually freed from Brainiac's ship and Kandor was returned to its normal size. It was situated in the North Pole, not far from Superman's Fortress of Solitude. 
At this time, Washington was attacked by Superman's old adversary Doomday. Zor-El and several other Kandorians assisted Superman in fighting him. Attacking Doomsday en masse, they brought him to the moon where they finished him off, seemingly killing him.
Taking the attack to heart, Zor-El then began pumping Kara for information of Kal-El's most dangerous enemies. Zor authorized the Kandorians to capture the most dangerous of these and bring them to Kandor, where they would be placed within the Phantom Zone. When Superman found out, he confronted Zor, Alura, and Kara, as several Kryptonians used lethal force against guards and police officers to capture the criminals. Kara was horrified at the revelations, and Zor was both surprised and remorseful about the deaths. Zor-El was then shocked to learn that not only did Alura know about the deaths, she had authorized the Kryptonians to use lethal force if necessary. 
Shortly thereafter, Zor-El was in New Krypton when it was attacked by Metallo and Reactron, as well as dozens of Brainiac Probes. The villains possessed Kryptonite, which made the Kryptonians vulnerable to attack. Reactron stabbed Zor-El through the chest, killing him. Funeral services for Zor-El were held at the Fortress of Solitude and were preside over by his widow, Alura. A short time later, Zor-El was resurrected as a member of the Black Lantern Corps and emerged from his crypt on New Krypton. 
Zor-El possessed the strength level of an adult Kryptonian male of his age, size and weight who engaged in moderate regular exercise.