Z-4190 bubble shield

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

Overview
The Bubble Shield projects a transparent, slightly white/gold tinted protective sphere around the user. The shield itself is similar to a geodesic dome, made of tessellating hexagons. The shield protects against bullets, explosions, lasers, plasma, flames, grenades, and other projectiles used primarily by the Covenant. Vehicles and players however, are still able to pass through it. After approximately 20 seconds has passed, the shield will collapse and the generator will self-destruct. Whether of Covenant or Human origin is unknown as there is little information and much speculation for both theories. Many point out that the Covenant Loyalists, mainly the Brutes, have been known to secure Human weapons and equipment for their own ends, thus pointing to the Bubble Shield as being one of Human development.

An early form of the Bubble Shield was used in the original teaser trailer for Halo 3. It is shown being used by Master Chief to protect him from an incoming Wraith mortar. In the teaser trailer, the Bubble Shield looked like a type of grenade leading to rumors that it would be one of the new grenade types.

Deployment
UNSC Marines are never seen deploying it during Campaign, while Brutes deploy it often. This leads it to be held as a Covenant Weapon and unlikely to be Human technology. At least one or two Brutes in a Covenant pack always have a Bubble Shield on hand. Brutes generally activate their Bubble Shields immediately when taking fire or feeling threatened.

Unlike the multiplayer "shield doors", vehicles are able to pass through the Bubble Shield. Once inside, if the vehicle, or anything else then damages the shield generator itself on the enclosure of the bubble, the shield will then collapse on fired detonation. Upon reaching its energy limit Bubble Shields will make a high pitched sound prior to overloading and breaking.

Campaign
When fighting large numbers of Covenant forces, the Bubble Shield is useful as it protects you from all sides. However, certain berserking Brutes would leap 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 19 or 20 seconds, the shield will deactivate, leaving you wide open to an attack. Another situation in which the Bubble Shield is useful is protecting you from a Scarab detonation. 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. Beware that the Scarab's debris will fall through the Bubble Shield, however, and could kill you. Another strategy is to use a Bubble Shield as a stepping stone, breaking up combat and allowing the player to use the Bubble Shield to fall back on. This is especially useful at the end of The Storm, where there are large, linear sections.

A good tactic when enemy troops deploy a Bubble Shield is to "take over" their Bubble Shield. Charging into a Bubble Shield often catches Covenant troops off guard, and enemies wielding heavy weapons such as Fuel Rod Cannons or Brute Shots will not fire at such close range. Bubble Shielded-enemies can easily be overpowered by melee or close ranged weapons as their teammates look on helplessly from outside.

Multiplayer
The Bubble Shield is an incredibly useful piece of equipment in any Multiplayer game or match. These are a few yet vital tactics that you should know if you want to use the Bubble Shield to its full potential. If you have 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. Also if you have a Shotgun or Energy Sword or a Gravity Hammer 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 be forced to come through the shield to finish you. Right before the player gets to the shield, pull out your Sword/Shotgun and surprise 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. If done correctly, the grenade would depletes the enemy's shields so you can kill them with a single melee hit or headshot.

Another method that is very useful is the Man Cannon Bubble Shield combo. In Valhalla and Narrows, campers often take position so that they can easily open fire at player landing from the Man Cannon. A player can use the Bubble Shield by sending it first, by throwing it onto the Man Cannon, thereby securing a safe landing zone on the other end of the Man Cannon protected from enemy fire and grenades. Also smart players can activate the Bubble Shield as they enter the Man Cannon, effectively giving them cover as they fly through the air.

Another 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. Another strategy is to rush into the shield and step back right when you're in front of it, if it works the other player gets out of the shield, giving you an open shot.

Another strategy is catch an opponent using heavy weapons by surprise by throwing a Bubble Shield in front of them as they fire. This calls for precise timing and close quarters. To pull off, a player must be within a reasonable close distance to the enemy and must deploy their Bubble Shield almost exactly as the enemy Rocket Launcher is fired. The activating Bubble Shield will cause the shot to explode in their face, often causing a suicide or giving the Bubble Shield deployer the kill.

Disadvantages

 * Enemies can enter the shield freely. This seldom happens in campaign as most Covenant units would stay away and wait for the shield to collapse. However, Flood Forms will usually and typically just run inside the Bubble Shield and attack you unlike other enemies who usually wait for it to disappear.
 * The shield does not stop enemy vehicles from entering, making it quite easy for them to splatter you since you cannot fire at them from a distance.
 * The Bubble Shield only lasts about 20 seconds. In combat, however, this is more than enough time to regroup and recover.
 * If either you or an enemy throws a grenade inside the Bubble Shield, it stays inside and will most likely kill almost everyone in the shield at the present time.
 * The generator is very delicate, so if you shoot at it from the inside, it will easily explode and destroy the bubble shield.
 * The Bubble Shield can be affected by other equipments if thrown within the shield proximity. For example, if an opponent throws in a Portable Gravity Lift near the generator, the equipment will lift it up, leaving anyone previously inside the shield defenseless. Additionally, effects from equipments can also be limited in the shield; if a Power Drainer or a Regenerator is thrown inside the Bubble Shield, only those within the shield are affected.

Trivia

 * The original Bubble Shield was smaller than the finished Bubble shield, as seen in the Starry Night video. It stuck into the ground rather then just lay on top of the ground, it also was originally in grenade form and seemed more like a personal device.
 * In an early Beta Version of Halo 3 the Bubble Shield was able to roll like the Power Drain, did not glow gold, had orange lights, and was able to protect you against the turrets guarding the outer perimeter of the multiplayer map such as Snowbound.
 * This shield resembles the description of the Onyx Sentinel shields in the Eric Nylund novel Ghosts of Onyx.
 * If you look closely at the Bubble Shield, you can see that there are actually two layers of shielding that make it up.
 * The range of the Bubble Shield is close to three meters and can cover an entire Warthog.
 * McFarlane Toys has made a Bubble Shield in the 2009 Wave 1.
 * In Halo Wars, a Shield Protector will deploy a Bubble Shield like object onto selected friendly units.
 * The technology for the Bubble Shield was developed by ONI, but oddly, the only AI characters that deploy bubble shields are Brutes, giving dispute to who actually made them.
 * It is possible to move the bubble shield by throwing another piece of equipment at its stand.
 * If a Power Drain is thrown inside an active Bubble Shield, the disabling effects of the Power Drain are contained within the Bubble Shield.
 * If you shoot at the enemy if he has already deployed the bubble shield, but the shield doesn´t appear, it still blocks damage.