Overshield

Overshields are a form of Covenant developed technology that strengthens the Energy Shields of the user.

Function
The Overshield technology is used by the Covenant to enhance their Elite warriors' shields by a factor of three. In Halo 3, these Overshields only boost a player's shields to 200% (although, MLG's playlists have a Custom Powerup Overshield that is of 300% strength). However it can also be used by any Spartan (in Mark V or VI MJOLNIR armor) or Elite who 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 for five seconds after the Overshield has been picked up. Once active the player's normal shield does not take damage until the Overshield is completely depleted (although any damage overlapping from something destroying the Overshield, for example a grenade's explosion, will also do damage to the player's normal shield). If the Overshield is picked up when the player's shield is below 100%, the player receives a full charge and the effects of the Overshield stay. In the single player Campaign the Overshield is reduced only when the player takes damage. In Multiplayer, it gradually depletes over time.

Appearance
A glowing red (gold and a cube in Halo 2) orb of energy encased in a glass cube. In Halo 3 the orb appears to be held together by several small magnets. After walking over an Overshield, the person's HUD shield display changes color from blue to red then green. Each color indicates one 'layer' of shields.

While wearing an Overshield in Halo 2 and Halo 3, the MJOLNIR armor is surrounded by a glowing force field which is easily seen even when wearing the Active Camouflage. This does not happen in Halo: Combat Evolved.

On the HUD, the shield monitor shows a light green for a fully charged Overshield, red for the second level, and the usual blue/purple (depending on player model) for the normal shields. The Halo:Combat Evolved Overshield shows yellow at the highest level rather than green.

Advantages
Overshields effectively triple the strength of the MJOLNIR and Elite armor's shields (only double in Halo 3). The shields can now protect the person from heavy weapons such as Rocket Launchers, Fuel Rod Cannons, Sniper Rifles, Fragmentation Grenades, and even Plasma Grenades (unless stuck). Also, while the shields are charging you are immune to conventional damage but will still be vulnerable to assassination, falling to your death and the Guardians.

Disadvantages
Due to the bright glow of the Overshields, the wearer is made more visible to other players, often drawing unwanted attention. In Multiplayer, the Overshield slowly loses its strength over prolonged periods of time, unless the player is a Juggernaut, VIP, or Grifball carrier. An Overshield can be fully depleted by an overcharged Plasma Pistol shot. Also, many players place traps near/on the Overshield, such as throwing Fragmentation Grenades or placing Trip Mines near it.

Note: The glow does not appear in Halo:Combat Evolved, and therefore has no disadvantages. The glow was probably added to balance the power up. Note: If in any rare circumstances you have Active Camouflage and the Overshield, you will not appear invisible due to the glowing effects of the Overshield.

Trivia

 * In the brief moment your Overshields are charging, you are invincible.
 * In HALO 3, you can pick up the Overshield (or Active Camo) as equipment if you have a piece of equipment and hold your equipment change button (default RB) and barely touch the Overshield. Then if you die you drop the Overshield, or if you pick up another piece of equipment you will drop/pickup the Overshield, allowing you to suprise your enemies, this works on matchmaking online.
 * The Overshield only appears in some Halo:Combat Evolved Campaign levels, it never appears in the Campaign levels of other games.
 * If you combine an Overshield with an Active Camouflage, you will appear invisible but still with the glowing outline created by the Overshield, thus defeating the purpose.
 * An easy way to kill enemies with Overshield its by sticking them with a Plasma Grenade or Spike Grenade, attacking them with a close combat weapon, or assassinating them (if you have the opportunity).
 * The first Overshield is seen in the Pillar of Autumn, in the Covenant boarding ship. Other levels with the Overshield in Halo: Combat Evolved are Truth and Reconciliation, the Silent Cartographer, 343 Guilty Spark, the Library, Two Betrayals, and the Maw.
 * In Halo 3 Multiplayer the Overshield only provides one extra shield, compared to two in the previous games.
 * The Meta, from Red Vs. Blue: Reconstruction, appears to have both Active Camouflage and an Overshield.
 * In Halo Combat Evolved, when you walk over an Overshield, your screen will turn pink for a second and you will hear the same sound as when your shields are loading.
 * In Halo 2 and 3, when you have an Overshield, one slice with an Energy Sword will not kill you. It will take about 2 hits.
 * In Halo 3, the Overshield charges much more slowly than before. An assassination still results in a one-hit kill, though.