A própria referência pode ser encontrada em O Sacrifício de Ruanon e não é explicada ainda:
There are ninety-one priests in all, Lone Wolf, said his Kai voice inside him. It seemed to have been a long time since he had heard its dustily cool tones. The number ninety-one was that of the Darklord Vashna, who chose it because of its factors, seven and thirteen – seven to signify the everlasting death-in-life and life-in-death that he possesses, and thirteen to denote the power of the Evil at his command.
These are the aspects of Naar that he was able to call upon to serve his will while he walked upon Magnamund; they will become his slaves once more should the Darklord be reborn.
A única referência dentro dos romances ou dos gamebooks que conectam os números sete e treze é da Guerra dos Magos . Existem 13 poderes mágicos no total, dos quais os sete primeiros são descritos como "magias menores".
There are thirteen Magical Powers, the first seven of which are called the Lesser Magicks
- Sorcery, Enchantment, Elementalism, Alchemy, Prophecy, Psychomancy, Evocation.
As Magias Superiores são:
- Thaumaturgy, Telergy, Physiurgy, Theurgy, Visionary, Necromancy
A implicação parece ser que, diferentemente do jogador (que deve selecionar suas habilidades na lista), Vashna tem o domínio de todos dos tipos de magia, ambos os sete. e os treze.