Okay, here are a couple more ideas I'll throw in the pot.
Try using the Ghast Template that Monte has for creating some Ghast Orcs. The link is http://www.montecook.com/arch_stuff13.html .
Also, why not a spectral Orc riding a spectral mount. That should be some scary stuff for a PC. Have the Orc flying through a wall should definitely be something that would frighten any PC. Make it even deadlier by making it the spellcaster.
I'd probably make sure that there is at least one Orcish archer in there as well. The makeup I'd probably have is 2 mounted fighters, 1 mounted archer, 1 melee person (give 'em a few levels of rogue to help flank anyone his mount engages), 2 spellcasters. Now that I think about it, I'd probably do:
Skeletal Orc Barbarian 4/Fighter 8 (Mounted Combat Specialist)
Skeletal Orc Fighter 10/ {Some Prestige Class} 2 (Mounted Specialist)
Skeletal Orc Barbarian 4/Ranger 8 (Archery Path, Elf and Human as favored enemies)
Skeletal Orc Barbarian 3/Rogue 7
Skeletal Orc Sorcerer 10/Barbarian 2
Wraith (or Spectre) Orc Cleric 7/Blackguard 4 (Make this the leader).
Try using the Ghast Template that Monte has for creating some Ghast Orcs. The link is http://www.montecook.com/arch_stuff13.html .
Also, why not a spectral Orc riding a spectral mount. That should be some scary stuff for a PC. Have the Orc flying through a wall should definitely be something that would frighten any PC. Make it even deadlier by making it the spellcaster.
I'd probably make sure that there is at least one Orcish archer in there as well. The makeup I'd probably have is 2 mounted fighters, 1 mounted archer, 1 melee person (give 'em a few levels of rogue to help flank anyone his mount engages), 2 spellcasters. Now that I think about it, I'd probably do:
Skeletal Orc Barbarian 4/Fighter 8 (Mounted Combat Specialist)
Skeletal Orc Fighter 10/ {Some Prestige Class} 2 (Mounted Specialist)
Skeletal Orc Barbarian 4/Ranger 8 (Archery Path, Elf and Human as favored enemies)
Skeletal Orc Barbarian 3/Rogue 7
Skeletal Orc Sorcerer 10/Barbarian 2
Wraith (or Spectre) Orc Cleric 7/Blackguard 4 (Make this the leader).