The complete history of Diableri is unknown. He existed in this universe during its infancy. He is a proemial being. It is said that he prepared what exist for what is to come. This was achieved by sowing chaos into order. Diableri along with several other beings were created to keep the balance of the Living Universe. They were the Proemial Gods.
These Gods helped to shape the Living Universe. Each of them had a task that they preformed to perfection. As they continued to preform their task their necessity to the Living Universe diminished, and the Proemial Gods started to fade from existence. Diableri became opposed to being erased from the Living Universe. He devised a plan to remake the Universe in his own image, with the hopes of preserving his existence. He created a race of small winged warriors who served as his eyes and ears. They were the Chaos Sprites.
Diableri led a group of Proemial Gods in a battle against the World Devourer Galactus. Many of those Gods died in the battle. Diableri himself was slain by Galactus. It is rumored that only three of the Proemial Gods survived the great battle Antiphon the Overseer, Aegis and Tenebrous, all of them were imprisoned in the Kyln prison planetoid located in a sector of space called the Crunch Cascade.