Board Thread:Versus Battles/@comment-24900075-20180417034833/@comment-24900075-20180417183022

It's less immunity and more that Zen'O doesn't have a nonexistence in the first place. He is one of the eldest void entities and literally predates "The Void" (AKA Nothingness). Erasing his nonexistence is the equivalent of erasing his existence, which needless to say is not required for him to "live".

Zen'O also has omnilock if you didn't notice, plus with Lavos' appearance I'm fairly sure Zen'O will have no problems using omniscience on it.