From Halopedia, the Halo wiki
Focus cannons are a type of energy projector similar to the capital-grade models used on Covenant starships. They can be individually tuned to allow for fine-excavation of Forerunner reliquaries or massive destruction of enemy ground forces.
The exact specifics on the operation of focus cannons are vague; while classed as a large type of plasma cannon, they generally operate by firing continuous streams of plasma at their targets - usually in a yellow-green colouration as opposed to the blue-red-purple of standard plasma weapons. As a form of energy projector, they presumably utilise the same magnetic confinement and anti-gravity technology to contain the plasma streams. A similar operation can be observed in the infantry-held M'tara-pattern focus rifle - with a similar beam colouration and operating mechanism.
The plasma streams fired bear great resemblance to the assault cannons of the Mgalekgolo, though it is unknown to what degree the two technologies are related. Some focus cannons, such as those of the Protos-pattern Scarab, can be observed dripping some kind of green, glowing fluid after firing - indicating that they may additionally use incendiary gel in their operation similar to the aforementioned assault cannons. Some models of focus cannon can be modified to support the injection and firing of infusion gel (itself a derivative of incendiary gel), further lending credence to this implication.
- Bloodfuel beam: a special variant of light focus cannon equipped on the Bloodfuel variant of the Locust walker used by the Banished.
- Infused focus cannon: a specially modified focus cannon created by Voridus to fire and spread infusion gel.
- Ultra-heavy focus cannons
- Protos-pattern Scarab - 1x ultra-heavy focus cannon - considered to be one of the most powerful ever fielded on a combat walker
- Deutoros-pattern Scarab - 1x ultra-heavy focus cannon
- Sumda'te-pattern Scarab - 1x ultra-heavy focus cannon
- Za'zayara-pattern Harvester - 1x ultra-heavy focus drill
- Type-29 Scarab - 1x focus cannon - considered to be the most powerful of all known Scarab types
- Heavy focus cannons
- Barukaza Workshop Scarab - 1x heavy focus cannon
- Zashk-pattern Draugr - 5x heavy focus cannons
- Light focus cannons
- Shua'ee-pattern Locust - 1x light focus cannon (alternatively termed a "charged plasma cannon")
- Barukaza Workshop Locust - 1x light focus cannon
The "light"/"heavy" classification of focus cannon (if any) for the following weapons is unknown, meaning where they are placed in the hierarchy of focus cannon power is presently unknown.
- Kmiro'sish-pattern Lich - 1x Emim-pattern focus beam
- Eklon'Dal Workshop Lich - 1x focus cannon[Note 1]
- Pnap-pattern Goblin - 1x focus cannon (select "Beam Goblin" variants-only)
A Deutoros-pattern Scarab's weapon destroying a vehicle.
List of appearances
- Halo 2 (First appearance)
- Halo 3
- Halo Wars
- Halo 3: ODST
- Halo: Reach
- Halo 2: Anniversary
- Halo 5: Guardians
- Halo Wars 2
- Winter Contention
- Halo: Reach manual, page 9
- Halo Encyclopedia (2022 edition), page 278-279
- Halo Waypoint, Scarab (Retrieved on Apr 13, 2016) [archive]
- Halo 2, campaign level Metropolis
- Halo Wars 2, Phoenix Logs: Infused Scarab
- Halo Encyclopedia (2022 edition), page 277
- Official Halo Wars Community Site, Game Info - Covenant Factory (Retrieved on Jan 22, 2010) [local archive] [external archive]