The death ray is a powerful ion cannon and the Olympus' best and most powerful weapon. It has enough firepower to destroy any city on Earth and is many orders of magnitude more powerful than a hydrogen bomb. It is this massive amount of firepower that has made Dr. Nylus obsessed with the death ray.
Routing more power into the death ray will drain power from the Olympus' shields, and vice versa. Careful timing is necessary as the death ray needs to recharge between shots.
This weapon could help the TSC win countless battles on Earth and would be an excellent defense against any returning alien forces.