S07:E74 - Lost in Time

Kai and Nya stow away aboard Krux and Acronix’s time travelling snake mech in a desperate attempt to save Master Wu. But when they arrive in the past, they must help the Elemental Masters prevent the Hands of Time from literally re-writing Ninjago history. Meanwhile, the the Ninja remain in the rapidly-shifting present trying to help Kai and Nya’s father, who was hit with a Time Punch.