Lost_6x15_quello_per_cui_sono_morti_ita_dvdrip_...

This episode is "useful" for understanding the Lost finale because:

: After discovering Mother killed their birth mother, the Man in Black leaves to live with the other survivors of the shipwreck. Years later, he develops a way to harness the Island's energy to leave. In a fit of rage and protection, Mother destroys his work. He kills her in return. Lost_6x15_Quello_Per_Cui_Sono_Morti_ITA_DVDRip_...

: It clarifies that the Island isn't just a place of mystery, but a cork holding back a darkness that could end the world. This episode is "useful" for understanding the Lost