Type-1 Antipersonnel grenade

"Get it off! Get...it...off!"

- A Grunt after being stuck with a Plasma Grenade

The Covenant Type-1 Antipersonnel Grenade, also known as the Plasma Grenade, Sticky Grenade, Holy flare, Holy light, or the Demon flare by the Covenant is similar to the UNSC Fragmentation Grenade in that it is a hand-thrown Anti-Infantry and Anti-Vehicle weapon.

Overview
The Plasma Grenade (or sticky as it is sometimes referred to as) is a specially designed explosive device (grenade) that sticks to its targets. Once it has made contact with a target, the plasma grenade will immediately bond to it, making any efforts of removal futile. The bonding mechanism holds its attraction until detonation, making it impossible to avoid its deadly explosion. Although it will bond to any target it hits, if it attaches to a piece of armor or a weapon, removing said articles will allow one to distance themselves from the explosion.

The "sticking" mechanism is complex enough to allow the plasma grenade the ability to distinguish between targets and inanimate objects. For example, it will stick to a soldier or a vehicle, but not a tree or a wall etc. This does not, however, allow the grenade to act selectively. The plasma grenade will not distinguish between friend or foe so accuracy and caution is strongly advised when throwing it, so as not to blow up your allies.

The plasma grenade possesses a timer. It has a three-second fuse that counts down at the point of activation. A manual activation via a small button or a stimulated activation, such as another explosion or gunfire, will set the detonator and start the countdown. Delayed activation can also set the detonator after it either sticks to a target or otherwise comes to a rest. It is possible to tell if the grenade has been activated. A densely small and bright cloud of plasma emission will leak around the grenade as the explosive reaction takes place inside. This cloud will gradually grow to a larger diameter after each second of the countdown. A low sound is emitted by the grenade when activated, followed by two rapid beeps and a high-pitched whine just seconds before the explosion. This is the plasma grenade's standard process of detonation.

The Plasma Grenade appears to have two settings: the standard three-second fuse and a delayed manual detonation. The latter is seen in Halo 3 by suicidal Grunts hoping to ensure their enemy's death by exploding right next to them. In addition, the plasma grenade like all grenades can be destroyed by being shot (Easily seen with the Sentinel Beam).

Also, some characters in campaign cannot be stuck. Brute Chieftains have immunity from this until their armor is knocked off. However if the Brutes shield is broken (i.e in Halo 2 Tartarus can be stuck if his shield is broken), you can still stick them.

Advantages
Sticking an enemy with the plasma grenade will always kill them when it detonates, except when oddball or juggernaught player is stuck and the option "Ballcarrier has extra life" is chosen (in Halo CE), but in this situation the ball carrier will only have 1 bar of health. Even a fully shielded Spartan or Elite (except on higher difficulty levels) cannot withstand a stuck plasma grenade. The plasma grenade is slightly more powerful than the UNSC Fragmentation Grenade. If it goes off at the base of the target's feet without bonding on the enemy, it will still result in a kill.

Disadvantages
The plasma grenade's bright blue glow and longer delay fuse allows enemies to easily notice and avoid it. It cannot be used around corners well, as it does not bounce, nor does it roll. A player wearing a fully charged Overshield may be capable of surviving the blast even when stuck. Also, if a smart enemy is stuck when they are too close they can simply run toward you to catch you in the blast zone. In Halo 2 and Halo 3, a primed plasma grenade in flight can be detonated mid-air by another explosion. Weapons capable of this include the Rocket Launcher, Brute Shot, Missile Pod, Frag Grenades, other Plasma Grenades. The Plasma Grenade will not stick to certain types of armor such as that of a Scarab or a Brute Chieftain's. When thrown at them, the grenade will fall to their feet, and they will probably notice it and move out of the blast radius. Ballistic or explosive weapons such as a shotgun or brute shot will remove the plating allowing the grenade to stick, If someone throws a plasma and it hits the wall, it can bounce off the wall back down and stick you.

Effects on Health
It has been shown that prolonged exposure to the radiation emitted by plasma grenades, without proper protection, can cause a deviation in the neural electric pathways of the user--a disorder called Boren's Syndrome. This disease can be fatal if the person does not get treatment. Avery Johnson is the only known person to have Borden's Syndrome.

Theory about "Stickiness"
''Note: The following is speculation.

The plasma grenade may stick by producing a thin layer of plasma which, when in contact with a target, fuses to the target. The reason the plasma grenade sticks to vehicles and characters may be due to an ability to sense heat. Body heat and the heat from vehicles engines is most likely what causes it to stick. Since a "dead" wall doesn't emit heat, it will however stick to the "living" walls of a Flood Hive. One problem with this theory is that it will stick even to exposed skin (on Grunts, Jackals, or Marines as an example) even though there is no metal to fuse to - it would be nearly impossible to fuse the grenade to flesh using heat alone.

It is also theorized that there is a complex internal mechanism built into the grenade that gives it this characteristic. A gravity generator may be built into the core of the device, giving it its own force of attraction. This artificial force of attraction is highly concentrated, which is exactly why the grenade is impossible to remove.

Another problem to the stickiness, is the reason when a plasma grenade is primed, it does not stick to the thrower afterwards. A theory for this could be that the grenade must be primed touching something emitting heat, then leaving the heat-emitting object, thus becoming "sticky," and finally landing and sticking to another object emitting heat. Or it is possible that it is equipped with a timer, so the thrower isn't stuck.

Another reason is the plasma heats up and is super heated and then by the time it touches it, it melts the armor or whatever and sticks to it.

It is possible that the grenade has an adhesive activated by a timer. Once the grenade is activated, this timer is initiated, giving a few seconds for the thrower to release the grenade. Once the timer has run out, the adhesive activates and the surface of the grenade is as sticky as glue.

It is also speculated that, once the grenade is thrown, a special, sticky plama escapes from the inside, spreading over the grenade. The fact that when the users activates a grenade, it doesn't appear to glow until AFTER it releases, and it seems to quickly spread.

Trivia

 * In Multiplayer if you stick 5 people in a free-for-all (i.e. Lone Wolf) match you receive the Lee R. Wilson Memorial Achievement.
 * In Multiplayer, if you stick an enemy with the plasma grenade you are awarded with the Grenade Stick Medal.
 * In Multiplayer there is sometimes an error where the stuck grenade will only kill the opponent, and not explode. There are also occasions where a Plasma Grenade will pass through the opponent or if it does stick, it may not kill them for an unknown reason.
 * In Halo: Combat Evolved the Plasma Grenade's explosion was more of a blue cloud and was also very powerful, similar to that of a Needler in Halo: Combat Evolved. The size of the blast animation and radius also got smaller going into Halo 2, and smaller still in Halo 3.
 * In Halo: CE, plasma grenade damage, like a needler detonation and plasma pistol overcharge, is classified as an EMP (electromagnetic pulse) and instantly drops all shields, even a full overshield. The same held for grenades that were dropped. This was removed in Halo 2 and 3 (except for the plasma pistol overcharge), making it less effective against infantry.
 * In Halo: CE multiplayer, the human frag grenade is considered more effective against large groups of infantry, while the plasma grenade is used for single opponents or fast-moving vehicles.
 * In Halo: CE, a plasma grenade inflicts 4 times the damage to a shielded Elite. So if an Elite is damaged by a plasma grenade at all when its shields are up, it will die, with few exceptions. However, the damage multiplier is normal when damaging flesh, so on higher difficulties an Elite has a better chance of surviving a plasma grenade explosion when its shield are down!
 * In Halo 2, when the Covenant use plasma grenades in battle, they will shout phrases as they throw them, such as "cleansing flame", "flare" and "holy light". This is similar to their belief of Halo. Rarely though they will shout demon flare even if it is thrown by an ally.
 * If John-117 throws a plasma grenade, the Covenant will call it a "demon flare".
 * Often times, when an NPC is stuck, they will have some type of reaction to being stuck.
 * Occasionally, if two plasma grenades are thrown in succession at the same spot; one will detonate, launching the other far into the air. The airborne grenade will explode in mid-air, causing a "fireworks" effect. This is easiest to perform in Halo: Combat Evolved.
 * If you stick a charging Hunter with a plasma grenade the Hunter will instantly turn around, exposing its back, when the grenade explodes, it is unknown why this occurs.
 * It is possible to stick a Hunter on the back of the head. It will charge at you, but if you manage to get away, then Hunter will die immediately.
 * In Halo:CE or Halo 3, if you throw a frag grenade where a group of plasma grenades are, the detonation of the frag will make the plasma grenades explode.
 * In Halo:CE, Plasma Grenades take 4 seconds to detonate. In Halo 2, they take 3 seconds. In Halo 3, they take about 2 and 1/2 seconds.
 * On one side of the Plasma Grenade, a Forerunner Symbol like that of an Halo:CE Elite is visible.
 * In Halo 3, when you throw a plasma grenade, it makes a long beep before exploding.
 * Plasma Grenades are favorite weapons of the "Ghosts" of multiplayer maps, nearly always sticking people in the face and chest.
 * In Halo 3, physics made it possible that if timed correctly at a position, when an opponent's Plasma Grenade is aimed at a player's left elbow (virtually), and when the grenade itself is about a foot away and the player throws his/her own Plasma Grenade, then both plasma grenades will stick each other and explode midway in the air.
 * It is possible to stick the grenade while it is in the opponent's hand, meaning they get to throw two grenades at you.
 * It has been found to be possible to stick yourself. Often achieved by bouncing a grenade off a wall, or by getting (un)lucky and throwing one onto your knee.
 * It, like all grenades, can be shot and detonated by a weapon. A sniper rifle works best.
 * It can be used for the Warthog Jump.
 * Occasionally, in Halo PC the Plasma Grenade will stick but will not explode and instead just disappear, called a "dud". It is unknown whether this is intentional or due to lag or a glitch.
 * Chieftains can only be stuck on their weapon, feet, and head (once the headdress is knocked off), although extremely difficult to do so.
 * Kamikaze Grunts will activate two plasma grenades at once and charge the player, they are the only species known to wield two grenades at once.
 * Avery J. Johnson got Boren's Syndrome from throwing all of the plasma grenades in a crate he stole from the covenant at Paris IV.
 * Plasma Gernades only stick to "organic" objects (Sangheili, Jiralhanae, Humans, etc.) and bounce off anything else, with the exception of vehicles.