THE ASCENSION. Buffyverse Term/Concept/Idea/Intratext.
In Season Three, Sunnydale mayor Richard Wilkins completes his long-planned "Ascension," his transformation into a giant, powerful demon. The Ascension is first mentioned in "Bad Girls" and progresses apace over the final nine episodes of the season.
The Ascension takes place 100 days after The Dedication, a ritual in which The Mayor becomes invincible. Thanks to an elaborate subterfuge in "Enemies," Buffy elicits significant information about The Ascension from Faith. Willow's theft of a page from The Books of Ascension (in "Choices') provides even more clues, as does the "Graduation Day," Part I testimony of Anya, the only living being who has actually witnessed an Ascension.
After completing another key step in the process, ingesting (in "Graduation Day," Part I) the Spiders of Gavrok, The Ascension finally culminates in The Mayor's metamorphosis in "Graduation Day," Part II into a huge snake-like monster while giving the commencement speech at Sunnydale High School. After eating Principal Snyder and several members of the SHS Class of 1999, The Mayor is destroyed when Buffy lures him into the high school library, full of high explosives.