Board Thread:Antaeus' Arena: Audience Chamber/@comment-1515612-20150915042519/@comment-5126368-20150918003042

Gaea can appear everywhere on Earth because she is the Earth itself. But ...

Apophis is the manifestation of Chaos and he can appear everywhere in any dimensions of Duat.

So I will vote for Apophis because he is so overpowered that you need to defeat him in all dimensions at the same time in order to defeat him (or just the Execration Magic). And since Apophis do not usually take a physical form, Gaea cannot hit him with the power of the Earth while Apophis can destroy the Earth with Chaos Magic.