Krux is one of the two current (and powerless) Elemental Masters of Time. He is the older twin brother of Acronix. Once a proud Elemental Master, Krux and his brother betrayed the Elemental Masters due to them believing that their element was the strongest. In response, their former allies forged a set of weapons that absorbed the twins' elements. Krux and Acronix were lost to the Temporal Vortex, but Krux managed to escape. For the next forty years, Krux conspired to strike back against Wu and Ninjago. As he awaited his brother's return, he bred an army of Vermillion snakes and took on an alias as a museum curator, Dr. Sander Saunders. He also kidnapped Ray and Maya so they could mold armor for the Vermillion, and build a time-traveling weapon, the Iron Doom. When Acronix finally returned, Krux had Cyrus Borg captured so he could complete the Iron Doom's construction. With Wu out of the action, the Ninja struggled to fight Krux, his brother, and their Serpentine army. Ultimately, the Iron Doom was completed, and Krux traveled back in time to defeat the original Elemental Masters. Using their Dragon, Kai and Nya made a final effort to thwart his plans. When the Iron Doom traveled into the future, Wu removed the Reversal Time Blade from the weapon, and it was lost in the Time Vortex. Though Kai and Nya escaped, Krux was lost along with his brother and Wu. He and his brother’s fates are currently unknown.