For example, you can completely avert the Balrog's spawning in Moria if you kill the leader and heir of the Orcs of the Misty Mountains, thus eliminating the entire faction by turning all of their settlements neutral. This can be bypassed if you manage to kill the factions' leadership before attacking the city, through either open battle or assassination.
Most of their units are on-par with those of the Elves. Any force of them will be a tough challenge.
Third Age: Total War provides examples of: Of course, there are many sub-mods for Third Age, with two of the most notable being the campaign-focused Divide and Conquer and the multiplayer-focused Third Age: Reforged.