It seems to me that this deal with Rathma, was unavoidable. This creates a ring, that is so overlooked, only those who are nearly immortal, will understand what was attempted.
From my own point of view, I am included in this ring, that returned my soul from the abyss through magic. By agreeing to form this pact with Rathma, I endure repeated visions of my own death, yet I continue to live. I am ever reminded of darker times.
I have completed letters in your past, of a passing 40 levels of this form of magic. I can tell your council that a necromancer, was not the choice a talent would have selected. To compensate the necromancer made use of summonings, as the attempted to disguise there ability as a conjurer. There is a difference, as the Conjurer is a source of ethereal hordes, that are the preferred weapon of Diablo.
The skills in magic advance at a normal rate, and can not simply be halted, by design. Should a necromancer fall though, there skills then advance as slowly as the undead. Any sorcery becomes sorcerous strength.
For skills that advance slowly, it is possible to break the curse. Reincarnation, is one possible result, should Rathma live on. These are the last of there time, and there spells are the last binding to the mortal coil. Please forgive there herbis, in attempting to live on, rather than be cursed to raise as the undead.
To break the curse, one of the rings must remain unbroken. The final acts are likely to break the pact with Rathma, but it would only make the arch demons more powerful. For now, several are only an echo, or under the control of sorcerery. In a few cases, the installation at the location is there strongest influence. The form of these artifacts counteract angelic and demonic essences. That included half-bloods. Without spells, you would die, your skills would slow to a crawl compared to your enemy. You might briefly reverse the effect accepting the curse of lycanthropy, or vampirism. But, eventually there result would turn any except a demi-god.