some people say when comparing omnipotent powers: "the one that strikes first wins".
some people say metapotence is straight up omnipotence (simplified omnipotence) although i've read that almighty magic might equal metapotence.
but i've also read it could be possible that monotheistic deity physiology could be more powerful than omnipotence, could be (although the rule of this wiki is omnipotence is number 1 power) and since anti-god could equil monotheistic deity physiology.
also on the page it says anti-god could be stronger than monotheistic deity physiology meaning anthrophy prevails, and since montheistic deity physiology is "omnipotent" metapotence would be defeated also since metapotence is "straight up omnipotence but simplified".
just a sidenote: metapotence is one of the strongest powers on the wiki...
i guess it depends on the author. and as antoniofer said, it could be either way.
All monotheistic deities aren't necessarily omnipotent. In fact most examples in fiction are nigh-omnipotent. The examples in which anti-god is equal to or stronger than monotheistic deity, those are the said supreme beings aren't omnipotent but nigh omnipotent. Metapotence is straight up omnipotence, not just an ordinary omnipotent power and can defeat an anti-god any day. Anti-Gods are at best nigh-omnipotent and thus are no match for metapotents. This is because an omnipotent being no matter how evil will still be considered as the supreme being due to being the strongest that there can be. eg- Lord of Nightmares is a purely evil omnipotent entity yet she is not an anti-god because of her omnipotence.
So, an Anti-God can never defeat a metapotent and this doesn't depend upon the writer.verse. If a metapotent being is defeated by an anti-god then the being was never metapotent to begin with.