As Leto Atreides II the God Emperor disentegrates, his last words to Siona Atreides and Duncan Idaho are, "Do not fear the Ixians, they can make the machines but they can no longer make arafel. I know I was there." After Leto Atreides II dies, Siona explains to Duncan Idaho that arafel is "the cloud-darkness of holy judgment." Arafel appears to be associated, by implication, with Kralizec "the typhoon struggle;" "the battle at the end of the universe".