Meridian obsidian (First edition)

In this final instalment in the Prophecies of Ballitor trilogy, Ben must defeat his nemesis, the pale man, once and for all. The pale man's only weakness is his obsession with Ben's mother. If Ben is to save the kingdom and reunite his own family, he must locate the mythical Cave of All Souls and exploit this weakness in the pale man's soul.

But no one knows where the Cave is located or if it really exists. The Book of Prophecies offers up a single clue: Meridian Obsidian, a hard, glasslike substance believed to line the Cave of All Souls.

When Ben comes across it in the most dangerous place he's ever been, he wonders whether the price for defeating the pale man is simply too high.