The Z-150 Directed Energy Laser Emitter/Biomaterial Incineration Apparatus, also known as the Sentinel Aggressor Beam or simply Sentinel Beam, is a Forerunner Directed Energy Weapon utilised by Sentinel Aggressors.

Overview & Background

The Sentinel Beam is a Forerunner weapon created in the waning days of the Forerunner-Flood war, designed to contain small-scale Flood outbreaks within research facilities. The weapon is directly integrated into the endostructure of Sentinel Aggressors, allowing it to directly draw from the drone's power supply when fired. However, the Sentinel Beam also contains an auxiliary battery, allowing the weapon to be salvaged and used in the event of an Aggressor's destruction.

Unlike Covenant directed-energy weaponry, the Sentinel Beam utilises a "Recharging Magazine"; energy is directly transferred from the power supply into a secondary energy receptacle or "magazine" before being expelled through the firing chamber. This energy transfer is a continuous process which requires no manual input, allowing the Sentinel Beam to recharge its "magazine" even while idle or being fired. However, the rate of energy transfer is relatively slow, thus it takes a considerably long time for the magazine to reach full charge if it is completely drained.

The Sentinel Beam projects a yellow-orange beam of superheated energy when fired, which is capable of travelling a theoretically unlimited range. Upon making contact with the biological target, a chemical reaction occurs due to the sudden temperature increase of the organic tissues, causing them spontaneously combust and set the target aflame. While initially small, continued exposure to the beam can aggravate and spread these fires before overwhelming the target and reducing their corpse to ashes. This makes the Sentinel Beam extremely effective at combatting the Flood, as its incendiary nature can heavily damage the unprotected Floods forms in addition to destroying any remaining organic matter, preventing it from being repurposed into biomass.

Despite its lethality against purely biological targets, the Sentinel Beam suffers due to its design as a basic tool for containing small-scale Flood outbreaks, as opposed to a weapon for use in direct combat; Energy shielding and objects constructed of inorganic materials (vehicles, armour) can withstand the superheated beam due to their different molecular structure. Additionally, there no known method for recharging the weapon's exotic battery, meaning the weapon must be replaced or discarded once its battery has completely drained.

Gameplay Information


  • The incendiary nature of the fired energy beam makes the Sentinel Beam highly effective against unshielded targets, especially Flood forms.
    • The Sentinel Beam will ignite targets if the beam strikes an area unprotected by Energy Shields or Armour. These flames deal additional damage and can finish off enemies without wasting the Sentinel Beam's battery power.
      • Ignited enemies will still drop grenades on death, which can take out additional enemies if they're cooked off by the burning corpse.
  • The Sentinel Beam has near-perfect accuracy which persists with its practically unlimited range, meaning it can be used as a makeshift sniping tool despite the lack of a scope.
  • The Sentinel Beam utilises a "Regenerating Magazine"; Instead of reloading or overheating, the weapon will passively refill its cache of usable ammo when not firing. Unlike Covenant energy weapons, the Sentinel Beam does not overheat after discharging the entirety of its magazine.
  • The Sentinel Beam will always have a full battery upon being acquired from a destroyed Sentinel Aggressor.


  • The Sentinel Beam is extremely weak against shielded targets.
  • Unlike Covenant energy weapons, the Sentinel Beam's battery cannot be recharged from a charging station, the meaning the weapon must be discarded or replaced once the battery has been depleted.
  • The Sentinel Beam cannot be obtained anywhere except fallen Sentinel Aggressors.

Developer Information



  • When picked up, the Sentinel Beam is referred to as an "UNRECOGNISED INCINERATION BEAM" by the HUD, presumably since the UNSC have not previously encountered and/or classified the weapon.
  • Interestingly, the way the Sentinel Beam is attached to Sentinels implies that the Master Chief is actually holding it upside-down.
  • While the Sentinel Beam's magazine can only fire 15 battery units, the weapon will drain more units when a single burst is fired. This is because the weapon's magazine is being constantly recharged even while it's being fired.
  • It is unknown if the weapon's incendiary properties are the result of modifications made by 343 Guilty Spark prior to the Battle of Installation 04, or if they are a standard feature of the weapon in SPV3's version of the Halo canon.


vde Forerunner weapons in SPV3
Incineration CannonSentinel RailgunSentinel BeamSentinel BoltshotSentinel Sniper BeamSentinel SuppressorSentinel Light Rifle
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