Fusion coil

This article is about the explosive container. For fusion cores in general, see Fusion reactor.

Four types of fusion coils.

A fusion coil, also known as a fusion core,^[1] is a container used for storing and transporting raw power.^[2] Fusion coils are used universally across multiple factions; different variants of the fusion coil have been manufactured by the UNSC,^[1] the Banished,^[2] and even the Forerunners.^[3] They can be used to power weapons and vehicles.^[2] Although fusion coils are used to store plasma, the Covenant made use of a similar technology with their plasma batteries.

Known types

All known variants of fusion coil are in the shape of a rectangular prism. They each consist of a metallic outer casing to protect the volatile materials within. The contained materials can usually be seen glowing from within the fusion coils, and the glow becomes more intense as the coil becomes more damaged.

UNSC fusion coil

This variant of fusion coil was developed by the United Nations Space Command to transport and store compressed superheated plasma. The container is made primarily out of glass and aluminum.^[1] One variant is colored matte brown, overlaid with what appears to be austere gold circuitry on the surface.^[4] A second variant is metal frame holding an amber, darkly-glowing, cylindrical object. When slightly damaged, the internal coil glows a warning red; when heavily damaged, it glows bright white. Stickers on the frame warn of radioactivity and high voltage. It emits a loud humming noise constantly.^[5]^[6]^[7]

Two UNSC fusion coils.
Another variation of UNSC fusion coil.

Blast coil

The blast coil is a variant of fusion coil developed and used by the Banished. It contains a highly explosive material that emits a yellow glow. When detonated, the coil delivers a powerful localized blast.

Two blast coils within a Banished base on Installation 07.
Small and large variations of the blast coil.

Plasma coil

The plasma coil is a variant of fusion coil developed and used by the Banished to hold plasma, in a similar fashion to Covenant plasma batteries. When detonated, the plasma coil leaves a pool of burning plasma behind.

A plasma coil at Outpost Tremonius.
A plasma coil after receiving damage. Notice the more intense glow.
Small and large variations of the plasma coil.

Shock coil

The shock coil is a variant of fusion coil developed and used by the Banished for powering their voltaic weapons. It contains electricity and emits a strobing blue light. When detonated, the shock coil emits large amounts of electricity that can arc toward nearby objects. It can also have the effect of an electromagnetic pulse on vehicles and other electronic devices.

A shock coil at a UNSC Forward Operating Base captured by the Banished.
Both sizes of shock coil next to each other.

Hardlight coil

The hardlight coil is a variant of fusion coil developed by the Forerunners. It contains purple hardlight energy that swirls violently within its casing. When detonated, the hardlight escapes, bouncing off of solid objects and disintegrating any organic material it comes into contact with, much like the hardlight projectiles fired by the Heatwave.

A hardlight coil.
Two hardlight coils within a Forerunner Beacon tower.
The larger variation of hardlight coil.

In-game information

Several shots from any weapon can detonate a fusion coil. In multiplayer, players often may attempt to lay an ambush for a hostile near a coil by tossing a fragmentation grenade towards the coil when the enemy forays near. Alternatively, they can be pushed from above onto passing enemies, exploding on impact with the ground, or used as anti-vehicle landmines at vehicle choke points. They have also been used for explosive jumping and in Forge to create perpetual explosions.

In Halo 2: Anniversary's Forge, there is an EMP variant of the fusion coil, much like how there is an EMP variant of the landmine.

In Halo Infinite, the smaller variation of fusion coils can be picked up and thrown by the player, as well as by enemy Jiralhanae. Like other items that can be held by the player, fusion coils can be picked up from a distance using the Grappleshot. In multiplayer, hitting an enemy Spartan directly with the fusion coil will kill them instantly. Killing an opponent in multiplayer with a thrown fusion coil will earn the player the Kong medal. Larger fusion coils are stationary, but have much more damaging effects when detonated.

Each variant of fusion coil in Halo Infinite performs differently:

Blast coils deal kinetic damage in a large area. Large blast coils have an even larger area of effect.
Plasma coils are effective against shields and leave a damaging field on the ground, similar to a Veporokk Workshop Ravager's charged shot. Large plasma coils spew plasma in an area before exploding and releasing their fragments, that leave the aforementioned damaging field.
Shock coils deal shock damage and have an EMP effect on vehicles. Large coils will spew electricity for a long time when damaged until they explode.
Hardlight coils deal hardlight damage and release bouncing projectiles on explosion, like those fired by the Heatwave. Large coils burst in even more projectiles.

Production notes

A Bungie Weekly Update described an incident where a beta tester used them, along with the Instant Respawn trick, to turn an Elephant into a "satanic piñata" on the Halo 3 map Sandtrap.^[8]
When saving a map variant in Halo 3's Forge, a brief "Terms of Use" agreement is shown. In the agreement, Bungie jokingly references the temptation to exploit these items, adding: "...And try not to build all your structures out of fusion coils."^{[citation needed]}
In the Halo 3 manual, under "The Forge" section, it references "Cooperate with your friends to make the work go faster, But don't forget to throw a fusion coil at them from time to time."

Gallery

The evolution of the UNSC fusion coil. Note that this item was not present in Halo: Combat Evolved.
Reference chart comparing between Halo 2, Halo 3, Halo: Reach, and Halo 4. Not to scale.
Sequence image showing the Halo 3 fusion coil's phases from damaged state to exploding state.
A radioactivity warning on the top of a UNSC fusion coil.
A fusion coil in a stable state in Halo: Reach.
A fusion coil in Halo 4.
Concept art of UNSC, Forerunner, and Banished fusion coils for Halo Infinite.
Concept art of a plasma coil for Halo Infinite.
John-117 using his Grappleshot to pick up a blast coil in the Halo Infinite Campaign Gameplay Premiere.
An achievement image in Halo Infinite featuring John-117 throwing a blast coil.
A damaged blast coil about to detonate in Halo Infinite.
A damaged shock coil about to detonate in Halo Infinite.
A damaged hardlight coil about to detonate in Halo Infinite.
A thrown plasma coil explodes in Halo Infinite.
HUD of the fusion coil in Halo Infinite.
A player with a fusion coil stance in Halo Infinite.
A Menachite-clad Spartan-IV prepares to throw a fusion coil at an Unggoy Conscript.