The Nemesis System was arguably the major selling point for Middle Earth: Shadow of Mordor. The system is designed to allow the player to disrupt the orcs' chain of command with targeted assassinations and completing certain events in order to lure out the big guys and eliminate them to hopefully have some of our allies take their place. Middle Earth: Shadow of War will, of course, have a bigger and better Nemesis System than its predecessor. It has to be this way considering that in the second game Talon is leading his own army, conquering entire regions. We now are able to see some of the details that will be introduced with the new system thanks to a new video published by IGN.
In the footage, Talon's objective is to conquer a fortress led by an Orc overlord from the Mystic Tribe. In order to make the assault at the fortress at all possible, Talon needs to weaken the influence of the tribe in the surrounding region. He does that the old fashioned way, by tracking down the warchiefs that lead the region and killing them. In addition, Talon is able to destroy the necromantic monuments that allow orcs of the Mystic Tribe to revive fallen comrades.
Once the Overlord's influence on the region is weak enough, Talon leads his army to assault the fortress and eventually kills the overlord. Once a fortress has been conquered, players will be able to choose one of their subjects to take the role of new Overlord. This choice can radically change the appearance of the region and the fortress. Appointing as Overlord an orc from the Feral tribe, for example, will increase the number of wild creatures roaming around and will make dragon baits available to use. Players will be able to swap their overlord with a different one at any moment.
This is apparently only a small part of what players can do with Shadow of War's Nemesis System. The introduction of tribes and the ability to change a region's appearance and nature, though, could make for pretty interesting gameplay situations.