The Sign

Walkthrough
The Sign is a quest given to you by Elaine about halfway through Chapter 3. Venture to the Den of Many Truths to investigate. Upon arriving in a cave, Kay and Griffith are interrupted during a discussion by a Mysterious Man, who introduces himself as Bassanius. Kay and Griffith will inspect the book at their own leisure, per Bassanius' offer, but are immediately teleported into the book itself. After an undisclosed amount of time and desperation on Kay's part, the pair is attacked.

After the battle, a portal opens leading back to the cave and Bassanius. Kay threatens to take Bassanius to Ascalia, assuredly to stand trail of sorts, however, Bassanius disappears. Having vanished without his grimoire, Kay and Griffith take the book with them.

Returning to the Castle will initiate a conversation about what happened. You will shortly be interrupted by Bassanius, again, who ultimately asks for residency in exchange for his knowledge in using the book.

Combat
Within the Grimoire Rewards 15XP Iridescent Ink x30
 * Defeat all enemies!

Enemies
Bassanius

Bolefolk

Bone Colossus

Familiar

Lordamarian Knight

Mau Nu

Shedurian Magus

Rewards

 * 15XP
 * Iridescent Ink x30
 * Mysterious Grimoire (?)
 * Bassanius