Another try
The Dwimmerlaik - horse
5 Black Numenorians
5 Orc Warriors - spear
2 Warg Rider - shield
Mordor Orc Shaman
6 Morannon Orcs - shield
6 Morannon Orcs - spear
Gorbag - shield
6 Orc Warriors - shield
6 Orc Warriors - spear
I really like this list. It has everything I want: a scary Ringwraith, a variety of models, more orcs than anything else.
Each warband can act independently. The Black Numenorians benefit from the Nazgul's Harbinger and with F4 D6 keep him safe so he can cast, cast, cast. The Wargs start near the Dwimmerlaik to engage anything fast that targets him. The Shaman goes with the Morannons to get the most bang out of Fury. Gorbag is the cheapest might I can get. He goes with the cheap orcs which I don't mind throwing away if I need to.
Will it work though? Is that the sort of Mordor army you don't want to face?