11 great Buffy The Vampire Slayer Episodes with summary (contains spoilers).
Angel:
In this episode Angels background is revealed and he vamps out in front of a shocked Buffy for the first time. Real trouble follows not long after when Darla attacks Buffy´s mum and the Slayer thinks Angel did it. Buffy sets out to kill him.
Prophecy Girl:
Showdown! Buffy against the Master. Great acting by Sarah Michelle Gellar in the scene where Buffy hears the prophecy foretelling her death.
Becoming Part 1 and 2:
Angelus plans to wake the demon Acathla to suck the world into hell, while Willow tries to do a spell to give him his soul back. Buffy has to kill Angel just as the spell works and his soul returns. We get to see more flashbacks about Angels past. Buffy runs away from home.
The Wish:
The demon Anyanka grants Cordelia the wish that Buffy never came to Sunnydale. The world turns into an alternate one where Vampires roam free in Sunnydale and Willow and Xander are Vampires. Cordelia frantically tries to right the wrong she did.
Graduation Day Part 1 and 2:
Buffy battles Faith and the Mayor who turns into a giant snake demon. In the end the school is destroyed.
Hush:
A group of demons called “The Gentlemen” arrives and steals the voices of all people in Sunnydale. Great acting in this “silent” episode.
The Body:
Buffy and Co have to deal with the sudden day of Buffy´s mum. Great almost “Vampire/Demon free” episode.
The Gift:
As the portal to a hell dimension opens and the end of the world nears, Buffy´s ultimate sacrifice saves the world.
Once more with feeling:
A demon summoned by Xander causes all Sunnydale to sing their best kept secrets and feelings. A musical extravaganza. The Buffy cast shows off their great singing voices.
Seeing Red, Villians, Two to go, Grave:
One of the best “mini arcs” is at the end of this season. After Warren kills Tara, Willow turns rampage using dark magic. First she skins Warren alive and then sets out to kill his two friends. Buffy tries to stop Willow and seems to fail when Giles arrives. A furious Willow takes Giles magic and sets out to destroy the world. It´s Xander who manages to save everyone with his unconditional love for Willow. As a crying Willows black hair turns back to red, Buffy finally realises that she loves the world and wants to show it to dawn.
Chosen:
Final battle against the First Evil. Anya is killed and Spike sacrifices himself. All girls all over the world who could be a Slayer are activated simultainously by Willow.