Protecting your city plays a big role in your success, and you have a lot of tools at your disposal to help fight off invaders.
Your Storehouse can be found near your Keep Building, and serves to protect a large amount of your resources from invaders who attack you. You can upgrade the building to increase the amount of resources that are protected by it. You can check what the current maximum amount of resources your Storehouse will protect is by tapping your Storehouse, tapping the "i" button, and then the "Stats" tab.
If you tap the “i” icon on this info screen, you can also see what the protection capacity is for each Storehouse level.
Your City Wall is another important way of protecting your City. In order to destroy your Keep, invaders must first destroy your City Wall and other defenses.
You can view your City Wall defense (maximum health) by tapping your City Wall, tapping the "i" button, and then "Stats".
If you tap your City Wall and then tap City Health, you can view the current health of your City Wall. Players who attack your Keep will reduce your City Wall health. If your City Wall health is completely depleted, you will be randomly teleported to another part of the map.
Upgrading your City Wall also increases the number of traps you can use to defend your keep.
You can research permanent upgrades for your Keep using the Maester Tower. Tap your Maester Tower building and then tap "Upgrade" (or the Hammer icon on your side icon bar) and then Idle Maester to review research options, including those for City Defense.
Note: If you do not have the materials required for some research upgrades, the game will show you the cost to purchase these in gold on the Research screen. If you obtain the materials for the upgrade elsewhere in-game, the cost will be reduced proportionally.
Troops that are in your city will defend it when you are attacked. To improve your troops, you can upgrade your Troop buildings, complete Maester research related to troops, and equip or craft gear that will buff your troops.
You can tap on your Avatar to view your Profile. The Stats tab includes much information about your total Troop attack, defense, and other buffs.
Note: Troops in your city that defend may become injured. Troops that are currently marching will not participate in City Defense and will not become injured by an invasion. If your troops become injured, you will need to heal them using Medic Tents before they can be used again. Upgrading your medic tents will allow you to heal more troops at once.
Traps can be produced by the Trap Maker and will be used to defend your City. The number of traps you can store in your city is based on your City Wall level. Different traps are effective against different troop types. You can tap the “i” icon on the Trap Maker Build screen for each trap to review the statistics for the trap and what troop types it is strong against.
When traps are used in battle, you can tap View Details in the battle log to see how effective your traps were and how many enemy units they defeated. Higher-level traps and traps which are strong against unit types you are being attacked by will make your traps more effective.
Note: Traps do not work unless there is at least one troop in the city to activate them.
If you are part of an Allegiance, you can ask other allies for help if you think you will be attacked. To do so, allies can tap your City and select Reinforce. The troops they send marching to your city will participate in City Defense. The troops can be recalled at any time, or will automatically return home after 24 hours.
Note: Up to 5 players may reinforce a single City at one time.
Peace Shields can be purchased from the in-game store (or earned occasionally via rewards in-game) and will prevent other players from being able to attack your City while they are active. You can use these to prepare your defenses and restore your troops after being attacked.
Note: Hostile actions will remove your Peace Shield, such as Scouting or Attacking another player.
Teleports can be purchased from the in-game store (or earned occasionally via rewards in-game) and allow you to move your City to another part of the map.
Two versions of a teleport can be purchased: a Random Teleport which moves you to another random space on the map, or an Advanced Teleport which allows you to Teleport to a specific area.
If the area of the map that you are currently in is highly contested, Teleporting allows you to better protect your City, as doing so will protect you from an incoming march.