Described as a monstrous, deadly tome that had survived every cataclysm since the dawn of civilisation, protected by dark spells and driven by special needs.
It was sought after by all who would uncover forbidden secrets that even Druids feared to posses. For those who craved dominion, it fed them powers and nourished their dark desires.
The evil in the world used it until the Elves managed to seize it. A few of the Elven magicians were unable to resist it and they were destroyed. The rest then decided to destroy the book, but before they could do so it disappeared. There were rumours of its use in the centuries that followed but nothing was ever confirmed.
When stolen from Paranor it subverted Brona and his followers, causing them to desire power for its own sake and for their personal use. They then abandoned all other goals, leading to the First War of the Races.
First King of Shannara
Bremen discovered the Warlock Lord was still alive and in possession of the Ildatch.
The Wishsong of Shannara
It was recovered by a sect of human followers of the Warlock Lord. These would-be sorcerers were not subject to the Sword of Shannara and so were not destroyed along with him. Sixty years before the events of The Wishsong of Shannara they took the Ildatch to their Eastland lair and began to delve into the magic. They were also subverted by the magic, becoming Mord Wraiths.
Allanon led Brin Ohmsford on a quest to destroy the book.
Indomitable / Dark Wraith of Shannara
It was later discovered that not all of the Ildatch was actually destroyed – one page had survived. This last page found new disciples, in the form of a band of Mwellrets.
Jair Ohmsford located the remaining fragment and eventually managed to destroy it.