Quote1 Kon somehow united the savage horde, honing them into a deadly army that ravaged Krypton-- and derailed its civilization for generations." Quote2
-- Harvest src

He was one of thousands of clones created and designed by Kryptonians. When the clones went berserk, he was able to lead them and make them into an army that reduced the lush gardens of Krypton to deserts, blasted great cities to rubble and slaughtered hundreds of thousands. However, while his clone army started out strong, the Kryptonians were better trained and had superior firepower. When the tide turned to the Kryptonians' favor, Kon lead his forces to take control of the towers that controlled the entire planet's climate.

Fearful of the clone seizure of the weather towers, since that would put the planet at risk, the Kryptonians launched a massive counteroffensive. They succeeded in killing all the clones, thanks to a secret agent who infiltrated Kon's inner circle. It is believed thar Kon died in the final battle, but his body was never found.

However, the damage was already done. Kon's army initiated a series of floods, quakes and other natural disasters that severely damaged Krypton. Rebuilding took decades, cloning became taboo and a doomsday cult which had a hand in the planet's total destruction was inspired.