Gomurr the Ancient

That Rank 10 power seems a bit powerful. Part of the trick of siege warfare in the game is successfully building and protecting your siege weapons until their in position. This power might disadvantage defenders too greatly, since he'd just need to show up every so often to pummel the defenses. I dunno. Depends on how much you're planning on being called, I suppose. Just sort of thinking aloud.

I might suggest also giving him a power (level 5 maybe?) that cancels the effects of Theoden's Glorious Charge, to illustrate how his bringing forth the Mumakil cut the power and momentum of the Rohirrim in the battle of the Pellanor. Your thoughts?

Personally, I think it's critical to be able to recruit 9 nazgul, as a group unit preferrably, but individual if it can't be done. But whatever you think is best. Otherwise it sounds good.

Here's a thought:

Level 7 or 8?

'Thrall of Saruman'

Saruman calls forth a miserable little cur of a man, similar to Wormtongue, who has stealth attribute or can appear as one of the enemy or something of the sort so he can sneak about enemy camps, and can steal resources, trigger a power that reduces moral and attack for units caught in the area for a long time, or 'cripple' a hero, preventing the targeted hero from using powers and perhaps reducing their attack rating for a long time. The thrall would use one of these three powers and then vanish upon completing his mission. Could be an interesting way or representing Saruman's more insidious powers and guile.

While I would oppose excluding a Celeborn hero, as he played a major role (in the Elves part of the war, at least) in directly leading the elves of Lorien to assail Dol Guldur. Arwen really doesn't deserve a character in this, so I certainly wouldn't oppose removing her, or Haldir for that matter. He's just a watchman raised in status to hero because of reasons only Peter Jackson can fathom... Elladan and Elrohir both had a more active role than those two, since they actually fought in the main battles of War of the Ring.

Brand could be good, though I'd have either Brand or Bard II, not both.