The Defense Core is a central point from which you can view all the factors that contribute to the Defense of your Base. It also allows you to acquire brand new Base Defense Add-ons, items that allow you to improve your Base Defense Bonus. You can acquire Base Defense Add-ons from the relevant tab in the Defense Core Building.
You must be at least Level 31 to build the Defense Core. Once you have built it, you may notice some terms that are unfamiliar to you. These are defined below:
Some structures in your Base - for example Defense Annexes and Defensive Emplacements - have a statistic that is called Base Defense.
Structures with this statistic are not Units, but they do actively participate in the Battles at your Base. Base Defense has the same value as Defensive Power, the statistic shown alongside your Units. For example, a Defensive Emplacement with a Base Defense statistic of 2,000 will be equal to 10 Units with a Defensive Power Statistic of 200.
In the Defense Core, the statistic "Base Defense" refers to the total value of all structures with a Base Defense statistic.
BASE DEFENSE BONUS
Your Base Defense Bonus goes towards improving the defensive performance of your Base. Remember that the Base Defense Bonus is applied only to the Units located within your Base (not in the Bunker), so if you haven’t got any Units there, you won’t benefit from this Bonus.
Your Base Defense Bonus also applies to structures such as Defensive Emplacements and Defense Annexes. Some non-defensive Buildings (e.g. the Radar) will begin to contribute to Base Defense Bonus once they have reached a certain Level.