The Plasma Rifle is a near to a medium range weapon, has a very high rate of fire, and inflicts very high shield damage. This weapon can also be used at long range if the user fires slowly and aims carefully, but this is usually not as effective compared to using this weapon at short range. Like other plasma weapons, the plasma rifle is very effective at depleting shields, though not as effectively as the Plasma Pistol's overcharged shot. The Plasma Rifle is also dual wieldable. A quick two second burst from two dual wielded Plasma Rifles into a Hunter's weak spot will kill it instantly. The Plasma Rifle is quite easy to aim at short range, so there is a big advantage against Flood Combat Forms because you can aim the Plasma Rifle at the center of the Flood where the infection form's sensory appendages are sticking out for an instant kill, but be aware of other Infection Forms, as they can revive the combat form if you do this, unless you quickly destroy the body. The Plasma Rifle also has an extremely fast melee attack, making it a good weapon to take out someone's shields, then quickly finish the job. An easy way to get a kill with a Plasma Rifle is to aim for the head. It will take about 2 shots to take out the shields, then another 2 shots to kill the person if you're aiming at the head, but only at close range. A commonly used strategy is to dual wield 2 plasma rifles then beat your opponent down. Also an effective strategy is to wield a plasma rifle and have an Assault Rifle or SMG in your holster, destroy an enemy's shield using the Plasma Rifle then either quickly melee them or shoot them with a solid projectile weapons such as the Assault Rifle for a quick and easy kill. This also works with the Plasma Pistol's overcharged shot. It is one of the only three weapons that appears in every level, in every game, in the Halo Trilogy. Also the Plasma Rifle, like most plasma-based weapons, does not need to be reloaded. If you blast it on “full-auto” without any pauses, you can fire 18 shots. This is more than enough to then switch weapons and finish them off with any other weapon.
The Plasma Rifle overheats very quickly when used in automatic firing mode and rapid firing. Also, the Plasma Rifle cannot be recharged by the player, so it must be replaced when depleted. While extremely effective at depleting enemies' shields, the Plasma Rifle doesn't deal as much physical damage as solid projectile weapons. The Plasma Rifle can kill someone by itself, but it takes a long time. Only when duel wielding Plasma Rifles can you kill someone within a quick amount of time. This can be avoided by dual wielding, a solid projectile weapon in your other hand, for example the SMG or the Spiker. It also runs out of ammo very quickly when in automatic firing mode. Also the animation for overheating partially blocks the screen, obscuring your view of opponents, and leaving you particularly vulnerable to their fire. In addition, the faster you fire, the less accurate the beams become, diverting from the original target more and more.
In both Halo: Combat Evolved and Halo 2, the Plasma Rifle's high rate of fire and moderate damage can be used to quickly neutralize low level enemies such as Grunts, Drones, and infection forms. Against enemies with energy shielding, the Plasma Rifle can quickly deplete that shielding and leave them vulnerable to a lethal headshot from an M6 Series pistol, Covenant Carbine or Battle Rifle, or sprays from an SMG. In addition, the valuable stun effect of the Plasma Rifle often stops or slows down the enemy long enough to prevent their melee. However, the plasma rifle can be ineffective against some enemies, notably the Hunters. Unlike in the previous two games, dual-wielding Plasma Rifles in Halo 3 is a very effective way of combating the Flood in campaign on all difficulties, most especially the shielded Elite variant, which often proves to be one of the most difficult campaign enemies due to their shields which can easily be depleted using the Plasma Rifle. Arguably, it is more effective than any other dual-wielded weapon. Due to the shield-taking nature of the plasma rifle and the armor-destroying capability of the SMG, it is best wielded with the SMG for close-medium range. It is also quite effective when dual-wielded against Hunters in Halo 3. However you must hit its weak spot, and better weapons are usually available for getting rid of Hunters. It is also good for Ranged Pure Forms in Halo 3. Dual Wielding two Plasma Rifles in Halo 3 in the level Cortana is very effective taking out infection forms and tearing apart combat forms; this tactic is very effective on higher difficulties. Many people have been known to complete Halo 3 using only this combination.
The Plasma Rifle has limited uses in Multiplayer, but is still a useful weapon, especially if dual-wielded or if playing on a close-quarters map. Dual-wielding increases the combined rate of fire and damage. Although its range limits the weapon to close quarter and medium range fire fights, if used properly a player can quickly dispose of a far away enemy but if it's possible you should get in close. It is also advisable to carry a mid to long range weapon such as a battle rifle or sniper rifle for backup against targets outside of the Plasma Rifle's range. It has the fastest melee attack of any weapon except for the energy sword, and it's melee is also powerful. In Halo 3, this weapon can easily overpower an assault rifle if the melee is used in conjunction well with the energy shield depleting shots, allowing an easy take down, however at medium range the Assault Rifle is likely to overpower the Plasma Rifle. The reason for the Plasma Rifle's superiority is the the fact that it is more accurate than the AR, yet does the same, if not more, amount of damage.
Variations Between the Halo Games
Halo: Combat Evolved
The Plasma Rifle in Halo:Combat Evolved is far more powerful and accurate than its Halo 2 counterpart. Also in Halo:Combat Evolved, the plasma rifle fires a little bit more slower than in the other games. Furthermore, the weapon held a unique ability to stun opponents that were hit by high velocity heated plasma rounds, this effect greatly reduces the victim's ability to move and dodge the incoming projectiles and allows the user to easily hold the opponent in the weapon's firing arc. However, the drawback was that this effect is only felt with continuous fire. While stunned, the weapon will often overheat before the opponent is completely killed. Despite this drawback, the stun ability is a useful and potent feature in the hands of an experienced user. In campaign mode, the plasma rifle is best used against the Sentinels and Elites. Sentinels always have a soft spot to Covenant weapons and it can be very useful in taking down Elites' shields when rapid firing. It should also be noted that this weapon behaved more like a rifle than its successor, having about twice the firing range, and that the plasma rifle decreases its accuracy while heating up, becoming even as inaccurate as its Halo 2 counterpart. However, this can be counteracted by burst-firing the weapon, releasing 2-3 bolts per firing. This will allow the weapon to be used for a longer period of time before it actually overheats, and more accuracy allowing you to hit long-range targets. Also, the rifle was much more bulkier than in Halo 2, like the Plasma Pistol and the Needler. Interestingly, it makes exactly the same sound as the Plasma Pistol.
Halo 2's Plasma Rifle is not as powerful or accurate as its predecessor and lacks the ability to stun. These drawbacks are compensated by a higher rate of fire and the ability to dual-wield the weapon, allowing it to be paired with a wide variety of other weapons from Halo 2 and creating powerful combination. The changes done to the weapon are directly related to the inclusion of dual-wielding and higher rate of fire. For purposes of balance, the plasma rifle, along with many others from Halo: Combat Evolved, was tweaked to better fit the new game's fighting style. The weapon takes an opponent's shields off with five shots, but it takes many more to kill. This version of the plasma rifle behaves more as sub-machine gun (SMG) rather than a rifle.
It has medium accuracy, but, when dual wielded, if both rifles are fired simultaneously, the accuracy will decrease greatly.
Plasma Rifles are also the basis for several other weapon systems, including the Twin Plasma Cannons on Ghosts, Halo 2 Wraiths, and Banshees. The weapon is not to be confused with the Brute plasma rifle, which is a faster, red version of the plasma rifle.
In Halo 3, Plasma Rifles are made even more powerful than their Halo: Combat Evolved and Halo 2's counterparts like most of the new weapons in Halo 3. Their bolts are graphically redesigned to have a more vivid look. The bolts seem to travel faster than those of its previous versions, reducing the need to "lead" or "direct" the shots at mid to long ranges. This may be because the plasma rifle is the signature weapon of the Elites, and following the Covernant Civil War they were free to tamper with the workings of their weapons, whereas before it was considered "perfect", due to the Covenant reverse-engineering it from supposedly "flawless" Forerunner technology. With a couple of minor adjustments, Cortana was able to increase the damage of ship-borne heavy plasma weaponry, so it is not too far of a stretch to assume the Covenant did the same at a smaller scale.
After a few shots the weapon becomes very inaccurate to fire, so you may want to consider shooting in short controlled spurts and bursts. Also, unlike in previous games, the plasma rifle is very effective against the Flood, even more so than its human counterpart. It takes 18 blasts when single wielded or 20 when dual-wielded to kill an enemy with normal shields in Halo 3, but one shot to the Infection Form roosting in the Flood Combat form will instantly kill it. This makes it effective against shields and semi-effective for flesh, making it a much more formidable weapon then its previous version. The weapon also gets a slight graphical overhaul, making it slightly more detailed and polished.