Aspheera, the former leader of the Pyro Vipers and a Hypnobrai sorceress, was once friends with Wu and Garmadon in her younger days. The two brothers had trespassed on Pyro Viper territory, nearly breaking a peace treaty that had been in place for a century when Aspheera met them. She even learned Spinjitzu, a martial art that involves manipulating elements, from Wu. Later on, she secretly overthrew Mambo V and became the new leader. However, her reign was short-lived as she was defeated by Wu and Garmadon using Forbidden Spinjitzu. Aspheera was then imprisoned in the pyramid for thousands of years, but she never forgot her grudge against Wu. She even gathered a legion of Pyro Vipers and Elemental Cobras to seek revenge after she was accidentally freed by the ninja.

More on Aspheera (spoilers): https://ninjago.fandom.com/wiki/Aspheera