The World Devouring stomach was obviously one of the greatest talents of the World Serpents. In fact, it was to the World Serpents what the Lightning Seed was to the Qilins, or Rebirth was to the Phoenixes.
This World Devouring talent was clearly incomplete, and was only capable of dealing with flames, but that didn't change just how shocking it was. Just by virtue of its existence, Empana had actually gained far more immunity against flames than even Ryu's Rebirth Flame allowed. It was truly shocking.
Just with this alone, it was clear that Empana's gains were excellent. In this regard, Ryu could only sigh.
If they didn't suppress his inner world, he could have allowed his other Summon to appear as well. Her gains would likely be just as great, if not more so, because her foundation was deeper than Empana's.