Hills Siege

Periodically, NPC towns will come under siege by the Obsidian Cabalists. The timing, duration, and location of these sieges are driven by Celestial Mechanics. When you attempt to enter a town under siege, you have the option to enter the Town Siege scene where the enemy has made camp outside the town and is fighting the town defenders. You can choose to join the battle and end the siege early or work your way around the perimeter, perhaps encountering only some scouting parties.

NPCs

 * Scout

Bosses
These Boss creatures will spawn once all 18 Siege Engineers have been eliminated from the Siege.

For a prediction on where the Cabalists will spawn : Moongate Travelers Siege Mapper!