Your level 1 Defensive Line is unlocked when you start the game.
The level of your Defensive Line determines three parameters:
- Defense - this measures how long your HQ can burn before you are automatically moved to another location on the battlefield.
- Defense Facility Capacity - how many Defensive Units (created by your Defense Factory) you can have at any given time.
- Defense Facilities Per Battle - how many of your existing Defensive Units engage in a battle when your HQ is attacked.
Why is my Defensive Line burning?
When your HQ is attacked by another player and you lose, your Defensive Line starts burning. Each time you are attacked and you lose it adds 30 minutes to the burning time. As your Defensive Line burns, it reduces your Defense number by 3 every minute. You can stop the burning by clicking the "Extinguish" button (which costs 50 gold) - doing so erases all of the burning time accumulated by all hits.
When your Defense is less than 100% you can click the green "Increase Defense 80" button to heal 80 points of damage, but you can only do that once every 30 minutes.
An important thing to note: You can increase the maximum number of Defensive Units you can build by assigning Reindeer to the Defense Department in the Assignment Center, due to his Defense Facility Capacity Battlefield Skill. You only need to have Reindeer assigned when you START the defensive unit build, you don't need to leave it assigned.