Fun project so far, here is what made it in, this is just testing, so nothing is carved in stone:
The nine black riders w/ robes, armor and their respective swords. They are a custom race and a custom class.
They are immune to normal weapons, paralysis, poison, and have an 85 shield rating, w/ 33% weakness to fire.
Their minimum level is 50 for the witch-king, and 40 for the other eight, and they will always be 25 and 20 levels above you, respectively (IIRC).
They are currently marked as essential, so best not to try killing them.
They are skilled in blade, block, blunt, & illusion (for future demoralize spell)
In daylight, from 7am to 8pm, they are 70% blind. From 8pm to 10pm, and 5am to 7am, they are 50% blind, and from 10pm to 5am they are 30% blind.
Someone brought up the idea of giving them detect life, according to the construction set wiki, NPCs do not make use of this.
Equipping the ring makes them 0% blind, increases their sneak skill by 100, and gives them a disposition toward the player of -200 for the witch-king, and -100 for the other eight.
and now the ring...
The ring is fairly simple so far. It gives 99% chameleon. I tried to do 100% chameleon, but at that point even setting the Black Rider's sneak to 500+ wasn't sufficient for them to detect the player.
With a chameleon level of 99%, boosting sneak by 100 seems to be sufficient.
The AI packages are iffy... The nine don't exactly run screaming for the player when you equip the ring... I hope to improve this in the future, if possible.
When they do react, they head for the last known location that the ring was equipped. Once they get there, they wander for 24 hours in the area, then return to their patrols.
If any modders have any ideas on improving the responsiveness of the AI, I'm certainly open to suggestions. Perhaps equipping the ring could force the 9 to reevaluate their AI, rather than leaving it up the game engine?
I had some issues with misbehaving Nazgul that delayed release... You bring 'em up the best you can... What are ya gonna do?
The last-known-ring-equipped location is tracked via an ingenious technique I found in the CS wiki called a "marker rat."
A lot of what the mod does isn't readily apparent, but a foundation has been laid for some hopefully interesting possibilities in the future.
Any feedback and ideas are welcome!
-Andy