Born out of the need for a powerful defensive mechanism for Brotherhood military bases, the Obelisk is quite possibly the most powerful laser weapon in recorded history, result of Project Obelisk WDTA2411 5. It's mode of operation remains basically the same throughout the wars - massive capacitors underneath the structure amass power, which is then used to create a powerful laser beam, directed against enemies via a system of advanced optical and focusing systems. Obviously, it requires massive amounts of power to function. In Tiberian Dawn, the Obelisk of Light is a sloped back obelisk that ends in a large focusing crystal that projects the laser. It's under complete computer control, with humans only needed to oversee that it works properly.