Gul'ron Dez Dire is an ancient text that translates to "Death of Worlds". It contained information about an interdimensional being known as Trigon, who is prophesied to bring about the destruction of all worlds through his heir. The book also speaks of the Trials, four hundred consecutive days of the harshest warrior training that have to be completed by Trigon's heir in order to defeat him.
The Tamaranean known as Koriand'r had Gul'ron Dez Dire in her possession when she traveled to Earth with the purpose of securing Trigon's daughter, "the Raven". After losing her memories and having them restored by Rachel Roth, the Raven spoken of in her mission statement, Kory tracked down the location of the spaceship that she used to travel to Earth. There, she found Gul'ron Dez Dire, which she used to explain to Dick Grayson and Donna Troy about Trigon, a being said to have the power to destroy all worlds. Kory informed them that if Rachel were to summon Trigon to Earth, it would be the beginning of the end. As they rushed to get to Rachel before she released Trigon, Donna learned from the book that Rachel was also the key to defeating her father.