What is a Domain..?

Your 'Territory' refers to your entire base (village) in the game, where you build structures and produce resources. The 'Territory 13' you asked about refers to the stage 'Season 1 - Highland of Mist' on the world map (Region 13). While there isn't a system where clearing a specific building unlocks the map, I'll outline the essential buildings and training methods you should prioritize in your Territory to increase your combat power and smoothly clear Region 13. Buildings to prioritize for clearing Region 13: Stronghold: This is the core of all your buildings. You need to upgrade your Stronghold to at least level 10-11 to expand other buildings to match the difficulty of Region 13. Training Camp: Region 13 is a section where enemy HP and attack power increase significantly. You should upgrade your Training Camp to level 10 to train 4-star heroes for your deck, or continuously run low-cost (Level 4) and ultra-low-cost (Level 11) training to constantly produce hero leveling materials (lunchboxes).

Stage!