Static Defense

These help you defend early attacks. They're unlocked by your first combat Structure, or your first upgrade Structure.

Overview
Static Defense Structures are a type of Mechanic intended to bolster Defender's Advantage in KoL. Static Defense Structures are placed when an incoming attack that can't be held off with units alone is identified. They're useful for defending early rushes, and turtle players in general. Static Defense comes in two forms: Primary and Secondary.

Primary
Primary Static Defense Structures are located within what is referred to as the "Main" tech path of each race. That is, the first Structure that unlocks offensive units also unlocks the Primary Static Defense Structure. For Protoss, this is the Shield Battery, unlocked by the Gateway. The Terran Barracks unlocks the Bunker, and the Zerg Spawning Pool unlocks the Spine Crawler.

Secondary
Secondary Static Defense Structures are unlocked by the Ground Unit Upgrade Structure for each race. They also double as Detection. For Protoss, the Forge unlocks the Phase Cannon. The Terran Engineering Bay unlocks the Missile Turret, and the Zerg Evolution Chamber unlocks the Spore Crawler.

Post Secondary
There are several Post Secondary Static Defense Mechanics that can influence the game in interesting ways. The Terran have two, in the form of the Planetary Fortress and the Shadow Ops' Self Destruct ability. The Protoss Dark Shrine has the Chaos Nexus ability, and the Hive utilizes the Swarm Cloud spell.