this is hard to call. at her peak, amethyst literally became the void in which the forces of order and chaos entwine. essentially becoming the focal point for all magical energies in the DCU... even becoming gemworld itself.
in a neurtal universe, i'm not sure how agamotto would do against that caliber of magic?
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Such is the magical potency of Agamotto that the Sorcerer Supreme, Doctor Strange, was unable to banish him back to his own realm, even when invoking the united strength of Dormammu, Cytorrak, Watoomb, Raggadorr, Denak, the Seraphim, the Faltine, Ikonn and Valtorr to fuel the spell.
IIRC, it says on panel something to the effect of "The great hunger threatened to consume Galactus at any moment" before they fight. Scan's posted in his respect thread, I think.