The Core — Joss Whedon

When Dawn falls ill, it's up to best friends Buffy, Xander, and Willow to join forces and find a supernatural cure in a world sorely lacking magic. The trio must fight their way into the Deeper Well, the former home of Illyria and other ancient gods known as the Old Ones, where they hope to jump-start magic back into existence. Collects Buffy Season 9 #21-25 and "Love vs. Life" from Dark Horse Presents #25-27.