Z-4190 bubble shield

The bubble shield is a 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 personnel, however, are still able to pass through it. After approximately 20 seconds has passed, the shield will collapse and the generator will self-destruct.

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. Damaging the shield generator itself in the bubble's enclosure will cause it to 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.
 * 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. This strategy is most effective with spike grenades, as the spikes will bounce around and shred anything inside the shield.
 * The generator is very delicate, and if shot from the inside, it will quickly explode and destroy the bubble shield.
 * Vehicles can also enter bubble shields. Therefore, you can run somebody over while they are still in the Bubble Shield.
 * The bubble shield can be affected by other equipment if thrown within the shield's proximity. For example, if an opponent throws in a Portable Gravity Lift near the generator, the Gravity Lift can 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 by throwing a power drain or radar jammer at the generator, causing both objects to roll, and leaving anybody previously inside the shield exposed.

Origin
Oddly, the manufacturer of the bubble shield has never been explicitly stated. It has primarily been seen deployed by Covenant forces in the later years of the war, suggesting it is of Covenant design. However, it has been stated that the technology involved with it is owned by ONI, and it is used by their Beta-5 Division strike teams.

The device itself bears little in common aesthetically with devices used by either faction. However, the geometric angles of the device vaguely resemble those used in Forerunner technology. In addition, the shield it generates is spherical and made of tessellating hexagons, which is similar to shields used by Sentinels and Protectors. As such, the bubble shield may be Forerunner technology reverse-engineered by the Covenant, which the UNSC then acquired for research. This would fit with the description of the similar drop shield, which is an "evolution of bubble shield technology."

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 shield 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 approximately 20 seconds, the shield will deactivate, leaving you wide open to 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 block enemy fire while retreating. 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 Guns 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 outside. Keep in mind that the Flood will usually just charge right in, so it is not much use against Flood forms other than the Ranged form.

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.

A similar situation can occur with plasma grenades. Activating a bubble shield as an opponent tosses a plasma grenade towards you can cause the grenade to bounce off the bubble shield and stick the player who originally tossed the grenade. The travel distance of this bounce is not far, so unless your opponent is charging into the bubble shield this does not happen often.

One anti-personnel 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 shredded by the ricocheting spikes. You can also activate the shield then use active camouflage, as the shields hides the ripples created by the invisibility.

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 the 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 players 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 invincibility power-up.
 * The bubble shield is replaced by the drop shield in Halo: Reach. It is a combination of the bubble shield and the regenerator. The bubble shield is much stronger than the drop shield, which could only take one Wraith shot.
 * If one looks closely at the deployed bubble shield, you can see it "pulses" as though the shield were breathing.
 * The bubble shield is capable of negating the effects of a kill ball, allowing players to go inside the ball.

List of appearances

 * Halo 3
 * Halo Wars
 * Halo 3: ODST
 * Halo Legends
 * The Package