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The Sentinel Beam is a Forerunner Directed Energy Weapon. Sentinel Beams are often integrated into the Sentinels from where the weapons take their name. The weapon is particularly effective against small Flood outbreaks and energy shields.


The Sentinel Beam was designed to contain and destroy small Flood outbreaks. Even though the weapons are integrated into the Sentinel's endostructure, it contains a secondary power source independent of the Sentinel and allows someone to salvage and use it if intact. The weapon projects a yellow-orange or blue beam of energy (reserved to the advanced Sentinel Majors), which is capable of effectively cutting through organic matter such as unarmored hordes of Flood -- Infection Forms in particular. Continuous contact from a Sentinel Beam can be devastating against any opponent, especially in Halo 3.

Like the Energy Sword and the Fuel Rod Gun, the Sentinel Beam cannot be used by players in Halo: Combat Evolved without extensive use of the Dev Mode. Such usage to acquire the Sentinel Beam involves using bump possession to attain a Sentinel and then switching back to Master Chief and have him destroy said Sentinel and exchange a weapon for the Beam. The beam is not visible from the first or third person view and if the player presses the fire button a damaging red beam will appear from the center of the screen. It later became usable in Halo 2 and Halo 3. A more powerful blue version of the beam is only available in Halo 2's campaign.

The Sentinel Beam runs on a non-rechargeable battery that runs out very quickly, yet even Sentinels created many thousands of years ago are capable of firing one. It may be possible that a Sentinel Beam attached to a Sentinel is powered by the Sentinel itself. It should be noted, though, that Sentinel Beams taken off of destroyed Sentinels often have some of the battery depleted. A possible explanation is that the Sentinel cannot power the weapon itself and relies on the battery but can recharge it outside of combat. Like the Covenant's plasma-based arsenal, it can temporarily overheat if 20% of the battery is used up in one continuous shot; the weapon vents excess heat extremely quickly in an attempt to counter this. In addition to being effective against the Flood, the Sentinel Beam's ability to rapidly drain energy shields also makes it an effective weapon against the Sentinels themselves.


Also worth noting is the version of the beam that the Monitor 343 Guilty Spark makes use of. In Halo 3, the construct uses the integrated weapon to destroy a couple of Jackals, a Flood Combat Form, mortally wound Sergeant Avery Johnson, and fight off John-117 and the Arbiter. The beam he fires is more powerful than and twice as thick as the usual Sentinel Beam, and is bright red rather than orange. When a monitor is killed, no Sentinel Beam drops from it so, it's possible that this beam is not a Sentinel Beam at all.

In Halo[]

In the Halo 2 campaign, the Sentinel Beam is a deadly weapon, easily capable of stripping the shields of an Elite. It possesses a decent rate of fire, amazing accuracy and range, and sustained attacks with the weapon inflict large amounts of damage. The beam's targeting reticle is also reasonably centered, making it easier to aim. The weapon's melee attack is about as strong as that of a Rocket Launcher, and is likewise considerably slow. The melee is also capable of disintegrating a Combat Form, although this process takes many hits and is impractical in most situations.

Two variants of the Sentinel Beam are seen in the campaign: the standard yellow-orange one in the silver housing, and the more powerful blue beam, which is encased in a gold housing. While the blue version is more powerful, it is also quite rare and will overheat faster than the standard version of the weapon.

The beam makes another appearance in Halo 3, with a few visual upgrades and several technical fixes. Unlike its Halo 2 counterpart, the weapon now has virtually infinite range and fires a much stronger beam that, if held consistently on an enemy, can destroy them within seconds. It is, obviously enough, extremely effective when used against Flood, and will cut down any form—including the vaunted Pure Forms—if aimed properly.

In Halo 3, the weapon does not spawn on any unaltered maps, and gametypes cannot be used to force it to spawn; it is only available in Forged map variants. This is likely due to the weapon's increased power and range, which make it devastating in Multiplayer matches.

Beam variants[]

The blue Sentinel Beam used by the Sentinel Majors is a more powerful variant of the common yellow-orange Sentinel Beam, though it also overheats quicker and its charge depletes faster. This difference is very similar to the relationship between the Plasma Rifle and the Brute Plasma Rifle.

The beams used by the Sentinels at Onyx were a golden color, with temperatures as high as 15,000 Kelvin.[1] Although this variation of the weapon took significantly longer to charge, it is thought to have been capable of depleting the shields of a Mjolnir Armor suit. Furthermore, Onyx Sentinels were capable of cooperating to generate golden beams capable of destroying entire Covenant cruisers. The power of the beams is one of many differences documented in the Sentinel variant's article; such differences are likely because Onyx Sentinels were guarding something even more important than the Halo Array: the Shield Worlds.


In Halo 2, it first appears on The Arbiter, where Heretic Elites used it as a weapon to attempt to stop the Arbiter and his allies from eradicating the Heretic force, in the Gas Mine. Flood Elite Combat Forms then used it on The Oracle, since almost all of the Elite forms were once Heretic Elites. Many of these weapons appear on Sacred Icon and Quarantine Zone, where the stronger blue beam versions were available from the many destroyed Sentinel Majors.

In Halo 3, it first appears on The Ark, where it can be gained by picking one from the Sentinels that are patrolling the area (although they may attack you if you destroy too many, or the Covenant Loyalists). Then it was seen on The Covenant, where some Sentinels were tasked to aid the Arbiter and John-117 in their escape from the Flood in The Arks's Citadel. When Master Chief, the Arbiter and Johnson arrive on the new Installation 08, they had to clear the Flood blocking their way to the Control Room with the assistance of Sentinels. When one of the Sentinels is destroyed, the Sentinel Beam will remain intact. When the monitor 343 Guilty Spark was destroyed, and the Halo ring activated, the Sentinels turned on the escaping Spartan and the Arbiter, causing several of the Sentinels to be destroyed, thus leaving the Beam weapons collectible to the player(s).

The Sentinel Beam makes an appearance in Halo 4 during the level Requiem when Sentinels defend the Cartographer against a pair of Hunters. This version is unusable, sounds lower in pitch than previous models and has a purple beam.



  • Ironically, it is a very good weapon against Sentinels in Halo 2 and Halo 3.
  • On the Halo 2's campaign level Quarantine Zone, provide two of your Elite allies with Sentinel Beams, and have them board the riding seats of your Spectre. Since NPCs can't run out of ammo, they make excellent weaponry. Unfortunately, further in the mission you have to leave the Spectre.
  • In Halo 3, the Sentinel Beam performs greatly against the Flood, as Infection Forms will burst if they are even slightly touched by the beam. Human Flood combat forms will die instantly, though Elite and Brute forms may take longer to kill. Aim for the Infection Form embedded in their chest and you'll kill it. Pure Forms are tougher due to their evolved forms; Stalkers and Ranged Forms will die by the time the weapon overheats whereas the Tank Forms will require two long blasts to the stomach to take them down.
  • In Halo 3, the Sentinel Beam is very useful for taking down a Brute's Power Armor quickly and effectively. It is also great for taking down Jackals and their shields as well as Grunts' armor, but it may overheat.
  • During the campaign it is best you only use it on Flood and Sentinels as it does much more damage to them than it does to the Covenant.


The Sentinel Beam is quite rare in multiplayer games but, if available, can be a powerful weapon in experienced hands.

Halo 2[]

Main article: Halo 2
  • This is best used in a small map like Warlock. It is also good in Headlong as long a you have other more powerful weapons with you.
  • If the Sentinel Beam is the only weapon you have, conserve ammo and rely on meleeing as much as possible. It has a quick and effective melee. Only fire the weapon when your target is far away, because ammo depletes fast. Melee in close quarters, and avoid deadly crossfire. Replace it as often as possible.
  • A Sentinel Beam is useful against unshielded foes, so a grenade to take down the opponent's shields followed by a burst from the Sentinel Beam can quickly kill an opponent.

Halo 3[]

Main article: Halo 3
  • During a game of Infection, the Sentinel Beam is an effective way to rid yourself of chasing Zombie forces, but take care as to where you aim, since the beam is easy to spot and is likely to give your position away if the shot goes astray.
  • When loading up vehicles, a Sentinel Beam in the passenger seat is an incredibly deadly tool. The most flexible location is in the back seat of a Mongoose, although the passenger seat of a Warthog or Prowler is also useful and advantageous to the match. The advantage of vehicle-bound Sentinel Beams is that it can 'clothesline' foes.
  • Steady shots can make the Sentinel Beam a great anti-sniper weapon. Fire at the sniper and then sweep the area. You will eventually meet your target, and they will have a difficult time evading the beam.
  • The Sentinel Beam has an extremely large power consumption rate, about 5% per second, so always carry a backup weapon and try to save the Beam for emergencies.
  • The Sentinel Beam was not available in any Matchmaking playlists, until it was featured on certain map variants used in the Bungie vs World playlist and the Maption Sack playlist. Its exclusion from regular matchmaking is likely due to the weapon's power.
  • When using it at long range, burst fire to make sure you don't waste its power. In close range, just melee or unload and you should get the kill.


  • In Halo 2, if a player throws a grenade while the Sentinel Beam is overheated, there will be no throwing animation.
  • In Halo 3, a fully charged Sentinel Beam will be left at exactly 77 charge after it overheats from a single continuous burst.
  • In Halo 5: Guardians, a variant of the Sentinel Beam known as the Safeguard Sentinel Beam is present. It functions largely the same as the standard version.