Two suggestions

[Gothmog]

1. Morgoth is known for having thralls in his service so why not have an occasional thrall spawn with one or two guards and when freed this thrall would receive randomised stats depending on the level you are on and he would help you fight your way through the dungeons until the end of the game or life you could also equip the thrall with equipment of your choice from your inventory

2. you should be able to wedge/barricade a door using weapons like what was done in Bailin's tomb in The Fellowship of The Ring, this would not only delay the enemy but it would alert you to their presence if they try to slam the door down

I would love if this made it into the game, thanks for reading