There are currently three types of Defensive Commanders available. They can be acquired after reaching a specific level of your Command Center .
Defensive Commanders function as important elements of any mid-tier to high-tier base. They are the guardians that either bolster up the attack speed of your towers, cloak your buildings using stealth, or annihilate attacking enemies in one single stroke. Currently, there are three Commanders available. All Defensive commanders have a 1 day time before they can be deployed again, and each deployment gives them additional experience (10 XP) that allows them to level up and become even stronger than before.
Defensive Commanders are powered by Commander Pylons that provide the bonuses. Once those are destroyed, the Commander needs to be redeployed.