Z-4190 bubble shield

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

Design Details
The Bubble Shield projects a translucent, 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. 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 it is 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. However, no Humans are seen making use of it during the campaign, and the only users are Brutes, suggesting the Bubble Shield is of Covenant design.

An early form of the Bubble Shield was used in the original teaser trailer for Halo 3. It is shown being used by John-117 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 to the theory that it is a Covenant device and not 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 when 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 in the enclosure of the bubble, it will explode, and the shield will collapse upon detonation. Upon reaching its energy limit, Bubble Shields will make a high pitched sound prior to overloading and exploding.

Disadvantages

 * Enemies can enter the shield freely, and the shield does not prevent vehicular carnage.
 * The Bubble Shield only lasts about 20 seconds. In combat, however, this is more than enough time to regroup and recover.
 * If either the player or an enemy throws a grenade inside the Bubble Shield, it stays inside and will more than likely kill almost everyone in the shield at that time.
 * The generator is very delicate, and if shot from the inside, it will easily explode and destroy the Bubble Shield.
 * Vehicles can also enter Bubble Shields. Therefore, you can run somebody over while they're still in the Bubble Shield.
 * The Bubble Shield can be affected by other equipment if thrown within the shield proximity. For example, if an opponent throws in a Portable Gravity Lift near the generator, the Gravity Lift will raise the shield generator up, leaving anyone previously inside the shield defenseless. Additionally, effects from equipments can also be limited in the shield; if a Regenerator is thrown inside the Bubble Shield, only those within the shield are affected. Likewise, if a Power Drain is thrown inside an active Bubble Shield, the disabling effects of the Power Drain are contained within the Bubble Shield.
 * The Bubble Shield can be knocked away with a well placed Power Drain or Radar Jammer thrown at the generator, causing both objects to roll, and leaving anybody previously inside the shield exposed.

Campaign
When fighting large numbers of Covenant forces, the Bubble Shield is useful as it protects you from all sides. However, certain berserking Brutes may leap inside the sphere and beat you down. It is particularly useful against Drones, partially because they usually surround you, and partially because they rarely attempt to enter the sphere. 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. As such, 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 and may end your moment of victory prematurely. 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 the outside. Keep in mind that the Flood will usually just charge right in, so it is not much use against most Flood Forms.

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, Energy Sword, or a Gravity Hammer as your secondary weapon, and a player with a regular weapon (i.e. 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 off. Right before the player gets to the shield, pull out your Sword/Shotgun/Hammer 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 will deplete the enemy's shields so you can kill them with a single melee hit or headshot.

Many players often deploy their shield and taunt their opponent by teabagging or simply doing a "staring contest". This can call for some embarrassing moments, as another player can easily flank and assassinate them.

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 players landing from the Man Cannon. A player can use the Bubble Shield by sending it first into 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. This tactic is useful if the deployer is holding a flag or oddball.

A 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 towards the shield and step back right when you're in front of it. If done correctly, the other player will overreact and step out of the shield, giving you an open shot.

Another strategy is to 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 this one off, a player must be within a reasonably close distance to the enemy and must deploy their Bubble Shield almost exactly as the enemy weapon 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.

One anti-shield combo calls for a Bubble Shield and a Spike Grenade. If someone deploys a Bubble Shield as protection, then another person can walk into the shield and throw the spike grenade at the inside of the shield. When the grenade goes off, the Bubble Shield will keep the spikes inside, and anyone unlucky enough to be caught inside the shield, unless they are on the opposite side, will be killed by the ricocheting spikes.

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 stand on top of it; it was also originally in a grenade form, seemed more like a personal device and looked similar to Invincibility, another piece of equipment.
 * In an early Beta Version of Halo 3, the Bubble Shield looked and rolled 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 Snowbound.
 * If you look closely at the Bubble Shield, you can see that there are actually two layers of shields that comprise it.
 * In Halo Wars, a Shield Protector will deploy a Bubble Shield-like object onto selected friendly units.
 * Although it appears in Halo 3: ODST, it cannot be used by the player or by other allies; only Brutes. This may be because of its extreme weight, weighing in at 20.5kg. This may also be the reason why Marines are not seen using it in Halo 3 and Halo 3: ODST. In fact, it may never had been intended for personnel-deployment purposes.
 * The Covenant Artillery is one of the few weapons powerful enough to destroy a Bubble Shield or the Invincible power-up.