9. Grave (Season 6, Episode 22)
Whilst controversial amongst fans, the Dark Willow saga is home to some of the show's best and shocking moments. Everything from Tara's sudden death to the worryingly graphic flaying of Warren is designed to leave the viewer's feeling disturbed and uncomfortable, and it's both commendable and somewhat despicable in that the Buffy writing team would go as far as they did with the storyline.
That being said, the final part of Dark Willow's quest for vengeance does lose a lot of the momentum that built up to its climax.
Things start off well enough with Giles and Willow going toe-to-toe in a magical duel, but things soon slow to a crawl when Willow goes off to end the world and Buffy spends the remainder of the episode trapped underground with Dawn.
Xander's 'yellow crayon' speech will always tug at the heartstrings, but considering the level of action and suspense that the previous episodes had, 'Grave' feels a little underwhelming by comparison. Having the Big Bad defeated in a more personal and intimate fashion is certainly a nice change of pace, it's just a shame that it comes at the expense of the story's momentum.