1 Kyros: This quest is much more important than recovering the ancient and shattered arcane Crown of Power. It's about me!
1 Alvissa: Figures.
2 Kyros: I have now mastered the magic of the four elements: fire, earth, water, and air. But there is one field of magic that eludes me.
3 Kyros: I seek an eldritch tome of ancient lore, that will grant me mastery over all else that remains!
4 Lambert: What's this book called?
4 Kyros: The Quintessential Fifth Elementalist!

Game publisher Mongoose Publishing is the current licence holder of several well-known role-playing games, and has also produced material for the Open Gaming Licence d20 System. Its best selling lines of supplements for the Dungeons & Dragons game was the Quintessential series, with titles such as The Quintessential Wizard, The Quintessential Rogue, and The Quintessential Barbarian.

Alas they never published the particular tome that Kyros is after here. Thus its great rarity and value.