Board Thread:Antaeus' Arena: Audience Chamber/@comment-1515612-20150328160505/@comment-3146930-20150405121815

This is a hard one. Both are incredibly ancient and powerful beings with any range of magical abilities in their arsenal. However I will say Tartarus would win based on a few events in the series.
 * 1) Gaea can control earth, but Percy and Annabeth mention during their time there that the ground and walls were more like flesh, giving Gaea little control over him.
 * 2) While Tartarus is able to make monsters stronger, it seems to have an opposite effect on our demigod heroes. It is possible that those not associated with Tartarus will also become weaker, even Gaea.
 * 3) Gaea was defeated by 3 demigods while all Percy or Annabeth could do was run. In fact just Tartarus taking form was enough for Percy to have a Blue-Screen-of-Death moment. Gaea appears before the demigods all the time during the series and all they do is get mad at her.

Based on this, I would say Tartarus is much stronger.