Defender Sphere



"When you pick it up, the Defender Sphere hovers above your head. It fires on any enemy who dares to attack you. The Defender also lowers by 50% the damage you take from enemy attacks. Handy, huh?"

- Ground Zero Manual

The only sphere item found in both single-player and multiplayer, the Defender Sphere protects its bearer by not only firing upon its master's attackers, but also reducing damage taken by 50%.

Strategies
The item is useful any time you find yourself in a tight spot. Its damage reduction is its most useful property, and it works even better when you have a good amount of armor.