Very good concept!
Forgive me for my English and for grammar mistakes! Because he wrote in a rush.
To put it bluntly, I both like and dislike Mordor for several reasons. One of the reasons why I do not like mordor is the Necromancer / Gorthaur / Sauron. The problem is that the logic of the development of the Dark Lord's power is not traced: the Necromancer is a wonderful hero supporting the hero and a terrible hero of direct action. If you do not score at least level 7 Necramancite, then you are doomed to fail against enemy heroes, which is not so easy between other things and it takes a long time. If you have level 7, then due to the dark cloud and the firepower of the Necromancer, you have at least some chances to defeat the enemy heroes, but if the enemy has a strong hero on the battlefield with a level of development (Glorfindel, Torin, Kelembribor, Aragorn, even Lurz at level 5 is able to kill the Necromancer! - and after all he is the ancestor of evil in Middle-earth !!!), then you will probably lose, and you will have nothing to give him in terms of confrontation of his hero. And the reason is simple: not very incomprehensible and unfinished system of development of the Necromancer, namely: terrible low damage, and a little above the average level damage at level 10 with all his abilities. Understand me correctly in terms of the destruction of enemy troops at level 10, he is normal, but against the key heroes of the enemy he is weak + to etomu in 4.5. Gandalf, Saruman, (and I think that Galadriel) get very strong bonuses.
The second. DieWalküre correctly noted that Gorthaur was much stronger and more powerful than Sauron with the ring, but the game is all the way around
Third: you are right AulëTneSmith that mentioned the moment with Gil Galad and Elendil. Indeed, few people in Middle-earth could fight with him! Also a very good example you filed with Aragorn! And I agree with you about the ability of direct action and weakening of the enemy hero for any form: Necromancer / Gorthaur / Sauron.
Also, judging by the words of DieWalküre, it follows that Sauron is gaining strength and power in the following order: Necromancer - Sauron with ring - Gorthaur.
The problem is that this chain looks like the Necromancer is a good supporting hero with an element of indirect destruction of armies and heroes, Gorthaur is slightly stronger due to direct damage (but his new three forms add a lot of new tactical moments) and - Almighty Sauron! At level 10, it can destroy all enemies alone (still! With such damage, and even in the area, and with the abilities of mass destruction !!!)
I understand very well that a very heated discussion is expected about Sauron, but I think that eventually this discussion will lead to the sixth significant and compromise proposal (along with Narya, Lady Galadriel, Ax Doriata, Ohranki Orkhank and Fredius proposal).