Castle Guard are specialized defensive Improvements that guard your Castle and battle for its defense.
In addition to counting toward your Castle Defense Bonus, they take part in each battle for your Castle, just like any other unit within your Castle walls. The advantage of Castle Guard over normal units is that the Castle Guard can be revived if fallen in battle. Once purchased, the Castle Guard will help you defend your Castle in all future battles.
To revive a fallen member of Castle Guard, simply click on them, and in a set period of time they will be revived and ready to fight in the next battle. The exact time required for each Castle Guard type can be found in its description window (open by clicking on the object), and can be viewed in a progress bar during the revival.
The fallen Castle Guard can also be instantly revived by your Friends. To revive your Castle Guard, your Friend must visit your Castle and click on the fallen Guard. Each Friend can instantly revive only one Castle Guard a day.
Each Castle Guard is designed to fend off specific unit types. A limited number of Castle Guard can be placed in your Castle. The Castle Guard cannot be dispatched to other Castles, Settlements, Battlegrounds or Beacons.
To purchase a Castle Guard, go the "Construction" menu and choose the "Improvements" tab. Castle Guard units will be marked with the text "More…" and a helmet icon.