Z-4190 bubble shield

The Bubble Shield is an anti-artillery and personal defense device developed by the UNSC's Office of Naval Intelligence branch.

Overview
The Bubble Shield projects a transparent, slightly white tinted protective ball. The shield itself is similar to a Geodesic dome, made of tessellating hexagons. The shield protects against bullets, explosions, lasers, plasma, flames and other projectiles used primarily by the Marine forces of the UNSC and the Covenant. A bubble shield is used in the original teaser trailer for Halo 3. It is shown used by the Master Chief to stop an incoming Plasma Mortar. However, in the video the bubble shield was in fact a type of grenade, leading to rumours that it would be one of the new grenade types. Vehicles and players however, are still able to pass through it. After a significant amount of time has passed or if the shield generator has taken enough damage, it will collapse. Covenant Loyalists, mainly the Brutes have been known to secure human weapons and equipment for their own ends, the Bubble Shield being one of the most common.

Development
The Bubble Shield was created by ONI. However it is not known if it was created with human technology or if it was reverse engineered similar to how the MJOLNIR Mark V energy shields were created. The Bubble Shield technology is nearly identical to the Covenant Shield Door's in function.

Deployment
Despite being UNSC technology, UNSC Marines are never seen deploying it during the Campaign, while Brutes deploy it often. At least one or two Brutes in a Covenant battle squad always have a bubble shield on hand. Brutes generally activate their bubble shields immediately following aerial insertion and when in large numbers.

Multiplayer Strategies
The bubble shield is a very useful piece of equipment in the multiplayer game. These are a few strategies that you should know if you want to use the bubble shield to its full potential. If you have just been in a close range fight with another player and your shields are down, it is often a good idea to use a bubble shield to give your shields time to recharge before you go frag your next victim. Also if you have a Shotgun or Energy Sword as your secondary weapon and a player with a regular weapon (Assault Rifle or Battle Rifle) is running to you, drop the shield so that they will come through the shield to finish you. Right before the player get to the shield, pull out your sword/shotgun and blast them when they step through. If you do not have a close range weapon, use this same strategy except with a Frag or Spike Grenade. Time the grenade so that it will explode right as they step through while you step out the other side of the shield to avoid damage. Another good strategy is to throw a spike grenade into the bubble; they ricochet all around, with multiple spikes hitting the doomed enemy inside. A good way to kill someone in a bubble shield is with the Sniper Rifle. Make sure you are in a safe position so you don't get assassinated and aim at the player's head. This is quite easy because people usually don't move when they are in a shield. Keep on the player's head and as soon as the shield disappears shoot them. While it may seem very simple most players do not see this coming and never expect it. Another fun way of getting through an opponent's bubble shield is to get a vehicle and drive into the player hiding in the shield. This works particularly well with a Warthog or Ghost and is very fun to watch as the victims believe they are perfectly safe.

Campaign Strategies
When fighting large numbers of Brutes, the bubble shield is useful as it protects you from all sides. However, certain berserking Brutes can go inside the sphere and beat you down. It is particularly useful against Drones, partly because they usually surround you, and partly because they will almost never attempt to go inside the sphere. Do be aware, however, that after a fixed amount of time, the Shield will deactivate, leaving you vulnerable to attack. Another situation in which the bubble shield is useful is protecting you from a scarab explosion. It will stop the explosion from harming you completely, unless the explosion starts on the inside of the bubble shield. So it is advised that you at least exit the scarab before using the bubble shield.

Trivia

 * In an early Halo 3 build the Bubble Shield was able to roll like the Power Drain, and the actual device had the same appearance, but had orange lights instead of blue. It was also originally in grenade form before being changed.
 * This shield resembles the description of the Onyx Sentinel shields in the Eric Nylund novel Ghosts of Onyx.
 * With no damage modifiers, a melee with most weapons will destroy the shield generator.
 * It is sometimes believed to be a Brute invention since Brutes always activate these devices, however it was developed by the UNSC.
 * The original bubble shield was smaller and was in the shape of a 'V', as seen in the Starry Night video. Also it would stab into the ground, rather then just lay on top of the ground.
 * In the Beta, the Bubble Shield did not glow.
 * In the Beta the Bubble Shield was able to protect you against the turrets guarding the outer perimeter of the multiplayer map Snowbound, however this was soon changed when the game was released for gameplay reasons.
 * You can actually move a Bubble Shield by throwing a Power Drain at the generator.
 * The bubble shield can also be moved by the usage of grav lifts.
 * The Bubble Shield logo, along with the Trip Mine logo, is a Halo 3 multiplayer emblem.

Cons of the Bubble Shield

 * Enemies can walk in and kill you.
 * The shield does not stop enemy vehicles from entering.
 * You cannot return fire while inside.
 * The bubble shield only lasts 20 seconds.
 * If an enemy throws a grenade inside the Bubble Shield, it stays inside and will kill almost everyone in the shield at the present time. Also, the grenade may detonate the Bubble Shield, increasing the damage, making it all the more dangerous to stay inside of it.
 * Flood forms will usually just run inside the bubble shield and attack you unlike other enemies who usually wait for it to disappear.
 * The generator is very delicate so if you shoot it will blow up.
 * If you throw a grenade while in a Bubble Shield it will stay in the shield and kill you.
 * The Bubble Shield's Shield appeared alot smaller in the Starry Night trailer.

Images
 Image:Bubble Shield in Action.jpg|The Bubble Shield. Image:Bubble Shield Logo.jpg|The Bubble Shield logo. Image:Avatars_Halo_Halo3_Shield.jpg|The Bubble Shield activating in the Starry Night trailer. Image:Bubble Shield Demonstration.jpg|The Bubble shield can block a Particle Beam Rifle shot. Image:1179249572.jpg|The Bubble shield is capable of blocking practically all forms of attack throughout it's duration, including Spartan Lasers. Image:Brute activates a bubble shield.jpg|A Brute activates a Bubble Shield. 