Darkhold

An ancient set of tomes created by dark wizards of Atlantis in conjunction with the malevolent entity known as Chthon. The spells in the Darkhold are universally wicked-- rituals designed to control, to kill, to manipulate. They are the blackest of magics and the book is dangerously easy for even unpracticed wizards to read and study. Single pages from the tome have been known to alter the course of history.

Known only to a handful is that the Darkhold serves as a conduit to the realm of Chthon. Though that entity is bound under Mount Wundagore, its spirit is free to travel. It is a fundamental nature of the Darkhold to corrupt the spirit and make a person greedy for more power. Prolonged exposure to a First God such as Chthon is more than most mortal minds can sustain without going mad.

The more one reads the Darkhold and uses it, the more power flows to Chthon. By invoking the darkest of magical efforts, a practioner could potentially summon Cthon, breaking him free of the chains that bind it under Wundagore and allowing him to return to its home-- or worse, to attack Earth.