Board Thread:Theories and Rumors/@comment-32134097-20181006173818/@comment-3214109-20181016003410

Ninja72 wrote: Mistake is dead. Also, how could Garmadon possibly do that?

The Oni can travel through realms and apparently can leave the Departed Realm at will. Mistake is dead and in the Departed Realm and she is an Oni and Sensei Garmadon is part Oni and I believe TA said he has more Oni blood than Wu so perhaps they can find the way to go back with the Oni and take Harumi along.

Anything can happen in Ninjago.