However, the ascension in ranks was the least notable gain from his journey to the Fire Elemental Plane.
Even if the Red Dragon did not kill those giants, the experience provided by the players would be enough for him to ascend within half a year. It was just a natural course.
On this journey, his greatest gain was devouring the elemental power of pseudogod nature within Ishmael.
According to Cassius' speculation, this was originally material the Sultan of the Fire Giants prepared for his own ascension, but Cassius accidentally "enjoyed" it earlier.
Becoming a god, a great and common goal.
Such things were not uncommon in the wicked inclinations of Erezer's forces.
For instance, that Githyanki ruler of the star realm, the powerful lich, Viraj 157th, devoured the strength and souls of higher-level Githyanki, using them as material for wish magic to pursue godhood.