[s4e7] It's: The Great Pumpkin, Sam Winchester

: Unable to defeat the demon with Ruby’s knife, Sam falls back on his controversial psychic powers to exorcise Samhain, a decision that visibly strains him and angers both Dean and the angels.

The climax takes place in a cemetery where Samhain has risen and trapped students in a mausoleum. While Dean rescues the students from zombies and ghosts, Sam faces Samhain alone. [S4E7] It's the Great Pumpkin, Sam Winchester

: While the show pronounces the demon's name as "Sam-hane," Sam correctly notes that the original Celtic festival is pronounced "Sah-wen" . : Unable to defeat the demon with Ruby’s

This episode marks a significant turning point in the series' mythology: [S4E7] It's the Great Pumpkin, Sam Winchester