The Aegis is a UEF Experimental Shield Generator. It generates a very large shield that can cover most of a base on its own, and it has a large amount of shield health. This shield does not regenerate on its own. However, it has the unique ability to completely regenerate its shield for 5,000 energy. This ability has a long cooldown and a huge cost, so use it wisely.
Note that this shield is only effective against artillery fire, as bombers can fly underneath the shield to damage the structure directly. Use the standard Shield Generators to protect Aegis from direct fire.
When used correctly, the Aegis can defend from very high volumes of artillery fire, they are best placed in pairs to negate the long recharge time
If done well, one Aegis supported by other vanilla Shield Generators will largely increase the survivability of a base. Huge volumes of shield health, properly supplemented by anti-air guns will virtually force your enemy to attack you with a land force.
It is wise to deploy some P-Shield Mobile Shield Generators or to build some stationary Shield Generators around Aegis. This is not only effective defense against bombers, but also in cases when the Aegis shuts down and must recharge.
The Aegis bears a striking resemblance to the Covenant Spires of Halo: Reach as both act as generators for large shields.