Grant
Grant asked Garon Whited:

Just listened to Sunset again and I got to the part where Eric slew the dragon. Did the Dévorer create the Demon King when he touched Eric's soul after Eric slew the dragon or was the Demon King created by the Demon eater's venom?

Garon Whited The chaos beast with the venom is a physical manifestation of a predatory creature from beyond the firmament. Since it was afflicted with a form while inside, it took on certain qualities in order to be a physical entity. One of these was a venom designed to temporarily suppress certain abilities in any other physical creature. That is all.
The Devourer, on the other hand, was a spiritual manifestation that had already taken over the majority of the mantle of the Lord of Light (the original one) and was in the process of adapting itself chaos creature to material creature to celestial creature.
The venom had nothing to do with it.

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