Origin
Corina used to be part of a coven of witches with Agatha Harkness and ancestors of Nico Minoru and Zoe Laveau. In 1428, near Wundagore Mountain, a mob with pitchforks and torches tracked them down intending to kill them for their witchcraft. The Laveau ancestor had talked the coven into summoning the demon lord, Valtorr, to defend them against the mob. Corina had her doubts about the plan, and those doubts would prove correct when Laveau reveals she never told the rest of them that the summoning spell requires a sacrifice. Corina was chosen and dragged to Valtorr’s domain, as she was believed to be the weakest among them. Agatha attempted to save her, but when Valtorr proved too powerful for her, she apologized to Corina and retreated, leaving her to suffer as Valtorr’s plaything. However, what Corina lacked in strength, she made up for in patience. Over what felt like millennia of torture , Corina slowly stole Valtorr’s powers until she was stronger than he, becoming Korrosion.
Creation
Korrosion debuted in Midnight Suns (2022) #1 by Ethan Sacks and Luigi Zagaria
Major Story Arcs
Rise of the Midnight Suns
Once she was powerful enough, she killed Valtorr and tried to exact vengeance on Earth. To do so, she targeted Zoe Laveau to enact doomsday on the world. First, she sent vapor minions to the Strange Academy to kidnap Zoe. Agatha was working at the school and was seemingly able to teleport Zoe to safety. However, Korrosion was puppeteering Agatha through an enchanted mirror in Agatha’s safehouse.
Fortunately, ever since the attack on the school a new team of Midnight Sons had come together to protect Zoe and the world from the vapor minions. They took Korrosion on one by one, but it was Agatha who finally defeated her. She stabbed Korrosion with a special knife that would release Valtorr’s power from her. After a small explosion, the two witches were believed dead.
Korrosion was actually returned to Valtorr’s realm, where she retook the throne