The Clone Wars S06E11 Voices

Yoda is deeply unsettled when he hears a voice from beyond the grave: the voice of Qui-Gon Jinn. Knowing that it is impossible for a Jedi to retain his identity after Death, the Jedi Council begins to worry that Yoda may be corrupted by the influence of the dark side. Determined to find answers, Yoda escapes the Jedi Temple to follow the disembodied voice.

The Clone Wars S06E10 The Lost One

A Jedi mission finds a lightsaber belonging to the long-dead Master Sifo-Dyas, prompting Yoda, Obi-Wan Kenobi, and Anakin Skywalker to begin an investigation into his decade-old disappearance. This sparks Darth Sidious to order Darth Tyranus to clean up any loose ends that may lead the Jedi to discover the truth of the Sith conspiracy.