The Clan Castle is arguably the most important defensive structure in Clash of Clans. This building can store units that will defend your base from enemy attack. Given that many units in Clash of Clans deal far more damage than your towers, the Clan Castle can be the strongest building you have on defense.
The Clan Castle also holds the loot rewards earned from Clan Wars. After a Clan War, your reward is automatically stored in the Clan Castle. It is not transferred into your normal storage structures and available for spending until you select the Clan Castle and select the “collect loot” option.
Clan Castle Upgrade Levels by Town Hall Level
As the Clan Castle increases in level, both its unit capacity and Clan War loot capacity will increase. As a result, it is important to keep your Clan Castle upgraded as you level up your Town Hall.
Note that the Clan Castle’s units can only be given to you via members of your Clan. Clan Castle units are all considered “donations”. One of the primary extrinsic motivators for joining a clan is to be able to receive units from clanmates in the form of donations. Note that donating units provides the donating player with credit towards an achievement along with a small amount of experience points based on the unit donated.
Clan Castle Upgrade Costs and Capacity by Town Hall Level
Clan Castle Strategy
The Clan Castle is one of your best defensive structures (if not the best defensive structure), but only when used appropriately. Below we will discuss the types of units you should try to get in your Clan Castle, where to place your Clan Castle, and the relative importance of upgrading your Clan Castle in comparison to other structures.
The Clan Castle is only as good as the units inside of it. Of utmost importance is to always keep your Clan Castle stocked with units, particularly if you are holding a lot of resources. A fully-loaded Clan Castle can literally be the difference between losing nothing and losing everything in an enemy raid.
For the purpose of cheap defensive units, Archers are the best bet. They are moderately effective due to their ability to shoot over walls. They also have solid DPS, making them good Clan Castle units. The biggest weakness of the Archer is that they are easily taken out by a Lightning Spell. Archers are also very weak when lured away from the base.
If you are in a clan that is willing to donate more expensive units or if you have an alt account, there are better options than the Archer. In particular, Wizards as well as the Dragon make some of the best Clan Castle units. Wizards deal great damage (and deal area of effect damage), while Dragons also deal area of effect damage, are flying units, and are difficult to kill (a Lightning Spell is not going to cut it).
Note that the Clan Castle can also be used for offensive purposes, especially for war battles. Trading powerful offensive units with clanmates or passing them along from an alt account can improve the strength of an attack significantly. One player donating a Golem (if high enough level), Hog Riders, Balloons, or a Dragon can significantly improve the strength of your attack.
Clan Castle Placement
Clan Castle placement is not terribly important before Town Hall 7. At Town Hall 7 and beyond, placement becomes very important. Players tend to neutralize the Clan Castle’s units by using a unit or two to pull the units out, then drawing these units to the corner of the base where these units are then summarily destroyed with little loss. At Town Hall 7 and beyond, players have enough buildings where it can be made difficult to lure out Clan Castle units.
In order to prevent Clan Castle units from being lured out, the Clan Castle must be placed in the center of the base. You can see the Clan Castle’s trigger range by selecting the Clan Castle and viewing the white circle. Make sure there is no drop zone within the white circle, and try to place buildings along the perimeter of this white circle to prevent enemy units from easily triggering your Clan Castle units.
Clan Castle Upgrade Priority
The Clan Castle should be considered amongst your higher upgrade priorities. Increasing its capacity will significantly improve your defensive strength. However, it is not your number one upgrade. It is usually a better use of builders to grab brand new structures and buildings while focusing upgrades on the Laboratory. Imagine the Clan Castle as the strongest defensive tower; it should be upgraded first before you upgrade any other old towers, but upgrading other structures and setting up an appropriate base layout for your new Town Hall level takes precedence.