First up, I myself would like a new Witch-King system as well.
But I personally don't like yours very much. It's a bit short, firstly, and secondly the abilities are not very exciting/special in my opinion.
What I like are the two Stances, although I would make that only available in his form as Lord of Minas Morgul, because only then he was actually using a mace, both in book and film.
Now to the abilities:
1) ...
2) I don't know exactly how I should look at this: Either from the Lore-perspective:
Yes, Witch-King could screech, or temporarily paralyze his enemies, or make them flee.
Or from the perspective of Edain 4.4.1, where this ability probably is op, especially the debuff does not Need to increase, since the enemies already can't do anything. But other than that, this ability is quite good, and it makes good use of the Slots.
3) This is the ability I dislike the most. Neither in the book nor in the movies he ever uses lightning. And if I remember correctly, Mouth of Sauron already has this ability, and I think it fits him better. I would Change this ability to the following:
Ghost form (as it is right now), and on the horse either
a) "Ringhunter", which makes him and Nazgul near him faster and do more damage;
or
b) Black breath, where he actively poisons enemys near him for a short amount of time. This would fit well with ghost form, as both abilities make him survive longer.
4) That ability has a little Problem, in my opinion: The Witch-King uses a Morgul Dagger, not a Morgul Sword. That means, I would only give him the active ability (I think he already has it), and interchange it with 3), so that it is earlier.
Then his "Morgul Lord" upgrade, after which he gets the different stances.
5) That is (by the Standards of 4.4.1, not in my opinion) already overpowered without doing any damage. But the thing with the gate is nice, since he helps destroy the gate of Gondor. Only Problem is, that Khamuls ability "Threat of the Nazgul" already has a similar effect. I don't know if the gate actually stays open for the full 60
minutes seconds the ability is supposed to last, AI at least closes it right away. But still, I would very much like it if the Witch-King could open gates.
Or, and that should be possible, he only resets the cooldown for everything except gates, which he destroys immediately?
So, as it is right now, I am
against your Suggestion, but maybe the System I proposed is better? I could make a more precise Suggestion, if someone wants to see that.
PS: The capital letters are because I'm German, and I can't be bothered to undo them after the autocorrection makes them.
PPS: Do you speak German better than english (your english isn't too bad, by the way)? If so, you could use the German part of the Modding Union. If not, that's of course not possible.Edit: Nevermind, I read your other post on Gulzar.