good units for a heavily themed night lords force;
- sorcerer and/or jump pack/winged lord w/pair of lightning claws
- deep striking terminators
- infiltrating chosen
- mechanised chaos marines and/or marine squads without heavy weapons (ie: only 'mobile' move & shoot style units!)
- raptors
- bikes
- mecanised havocs w/special weapons
- predators
- land raiders
anyways, that's how i would limit myself to unit choice were i to do a nightlords army!
cheers!