For everyone who has or is about to see this episode of Buffy (seen by me this evening after everyone (but Riaz) had gone to bed), the word you might want a definition of is: fulgent:
ful·gent (f
l
j
nt, f
l
adj. : Shining brilliantly; radiant: ìtower searchlights . . . as fulgent as half a billion candlesî (Nicholas Proffitt).