Overshield
From Halopedia, the Halo wiki
Overshields are a Covenant technology that strengthens the Energy Shields of the user.
Overview
Function
The Overshield technology is used by the Covenant to enhance their Elite warriors' shields by a factor of three. However it can also be used by any Spartan in MJOLNIR armor that might come upon it. When picked up, it takes approximately three seconds to completely charge, but during the charging period the player will be invincible. When it is active, the normal shield does not take damage until the over shield is completely gone (although any damage overlapping from something destroying the over shield, for example a grenade's explosion, will take the full rest of its effect on the original shield/health). If the over shield is picked up when the shield is down, the player receives a full charge and the effects of the over shield stay. In the single player game, the over shield is reduced only when the player is hit, while in the multi player game, it also weakens at a constant rate.
Aesthetics
It looks simply like a red ball (gold in Halo 2) of energy encased in a glass cube. In Halo 3 the ball of energy appears to be held together by several small magnets. After walking over an over shield power up, Master Chief's HUD shield display changes color from blue to red then green. Each color indicates one 'layer' of shields.
When wearing an over shield in Halo 2 and Halo 3, the MJOLNIR armor is surrounded by a glowing force field, which is easily seen even if you are also wearing the Active Camouflage.
Advantages
Overshields effectively triple the strength of the MJOLNIR and Elite armor's shields. The shields can now protect the user from heavy weapons such as Rocket Launchers, Fuel Rod Cannons, Sniper Rifles and even a sticked Plasma Grenade (only if fully charged).
Disadvantages
Due to the bright glow of the Overshields, the wearer is more easily visible. Also, the Overshields can be taken out completely by an overcharged Plasma Pistol shot. When the overshield takes damage, it takes more time for the shield to actually recharge. The shield also gradually loses energy, except in Halo: CE, or if you are a Juggernaut with them.
