Power drain

The Power Drain is a short-range, tactical, energy sapping device which made its debut in Halo 3.

Function
The power drain creates a short-range Electromagnetic Pulse (EMP) effect which causes disastrous failure of powered field systems within a set radius, and is designed primarily to interfere with common varieties of electrical field-based shielding, vehicles and power generation. It also has a damaging effect on biological systems and can wound or kill most bipeds in its resulting explosion.

Essentially, the Power Drain is a reverse to the Regenerator; instead of energizing a player's shields, it causes any player's shields within the area of effect to drain away quickly, making them vulnerable to harm. The self-destruct explosion after the activation of the Power Drain will not kill you (If you were at full armor health previous to deploying it), but will take your health to critical levels. The Power Drain can also disable vehicles via EMP, rendering them unable to move (but the vehicle can still use and aim its on board weapons) when they drive or fly through it and even about five seconds afterward. If a Regenerator and Power Drain are deployed in close proximity, the Regenerator will stop working.

The Power Drain, like the Bubble Shield, Trip Mine, Radar Jammer and the Portable Gravity Lift, are all in the category of equipment and can be deployed using the "X" Button. It activates shortly after it is thrown - just enough inactive time to travel away from the user, leaving them unaffected.

The power drain can even disable non-drivable vehicles like the Scarab as seen in TGS Demo Part 2, but the weapons systems will still be active, as in any vehicle. In fact, the power drainer will affect any device that runs on any type of energy within its radius in game.

Tactics

 * This equipment will stall a vehicle's engine, but the weapon/weapons on the vehicle still work, working quickly with the Power Drain and a weapon or grenade is the only smart way to kill everyone inside a turreted or armed vehicle.
 * This is a good piece of equipment that is well used in conjunction with headshot weapons such as the Battle Rifle and Magnum.
 * This is the piece of equipment that is a must need when outnumbered, once drained, the whole group becomes a big one-hit-kill target.
 * Bubble Shields cannot block the Power Drain from entering, so it's a good idea to throw one inside of a Bubble Shield while your enemies are inside of it.*If the Power Drain unit hits the Bubble Shield unit, the Bubble Shield may move, depending on how fast the Power Drain is going at the point of impact. This can sometimes rob your enemies of the shield's protection, making them incredibly easy targets and can lead to some rather degrading deaths. A particularly humiliating example of this tactic can be seen in a Top Ten Series episode.
 * Deploy this equipment near a popular sniper position or an area where people land after they get off of the Man Cannon, after that, its another one-hit-kill target.
 * Try keeping some distance between you and your foe when in combat, as when in close quarters battle, they tend to use power drains.
 * While it is pure luck when it happens, it is possible to splatter an opponent with a Power Drain by tossing it down a hill and it hitting them while it is rolling.
 * The Power Drain's ability to render vehicles temporarily useless is only featured in one other weapon in Halo 3; the Plasma Pistol's overcharged shot.
 * The Power Drain is a great way of 'jacking' an enemy's vehicle. For example, you can throw one at a warthog, and then when they're low on energy shields, 'jack' their vehicle and it will most likely kill them and gain you a vehicle. Also, if a banshee is close to the ground, a power drain can force it down, then you can steal their vehicle and get the "Skyjacker" medal.
 * Strangely, if your vehicle gets 'Power Drained', if you get out and get back in the engine sometimes seems to work again even with the power drain active.

Spawns

 * Avalanche- There is one Power Drain each located near the large Mancannons of each base where the Mancannon leads players inside the top of the base.
 * Blackout- The Power Drain is on the floor that is above the tunnel hole where the Shotgun spawns.
 * Cold Storage- The Power Drain is on the second floor where it is above a Teleporter and Assault Rifle spawn room, and also in between another Teleporter and Plasma Rifle spawn.
 * Construct- There are two Power Drains on the map. One is located at the bottom floor, very close to the Yellow Gravity lift. Another is located at the column where the Energy Sword spawns on the map.
 * Epitaph and Epilogue- On Epitaph, the Power Drain is located at the lower floor where the large Gravity Lift resides. On Epilogue, it is located at the higher floor. (Originally the Needler spawn).
 * Foundry- The Power Drain is located on top of the nearest center-positioned Box from the bases, along with the Plasma Pistol spawn.
 * Ghost Town- The Power Drain is located on the upper floor where the main building is.
 * High Ground- The Power Drain is located at a balcony near the room where the base's Needler spawns.
 * Last Resort- The Power Drain is located inside the Fortress, near where two Assault Rifle spawns.
 * Narrows- (Updated version) There is a Power Drain near the each of the base's Mancannons. (Older version) The Power Drain is located near the Yellow base's Mancannon.
 * Sandtrap- Two Power Drain spawn under the structure where there is a Gravity Lift and where the Rocket Launcher spawns on the map.
 * Snowbound- The Power Drain spawns at of the Blue Lower Base.
 * Standoff- There is a Power Drain each inside a base's lower room, the room where the controls for the Window shutters and another Entrance gate are.
 * The Pit- There is a Power Drain on the upper floor just outside the room where the Energy Sword spawns outside the map.
 * Valhalla- One Power Drain spawns at each base's upper floor.

Trivia

 * The Power Drain lasts approximately 6.5 seconds.
 * The Power Drain, Radar Jammer, and Flare are all visually identical, save for the color of the glow each item emits.
 * In the Multiplayer Beta, the players got the Power Drain and the Bubble Shield mixed up and ended up draining the shields of friendlies and shielding enemies. The Beta version when deployed, was a glow of a much lighter blue color and had a larger effect radius which had a cloud of haze around the edge.
 * When the Power Drain is thrown at the generator of a Bubble Shield, the Bubble Shield will actually move over a few inches when hit by the Power Drain.
 * It may also be used as a grenade by throwing it at a group of enemies, draining their shields and after a little while, the resulting explosion can sometimes kill the unshielded foes if they are close to it.
 * The Power Drain can be thrown through the shield doors on all levels and through a deployed Bubble Shield. This is a very efficient way to root out campers.
 * If you fire a Spartan Laser while near a Power Drain and view the beam in Theater mode from within the Power Drain's field, the beam will be a blue-white color.
 * A common strategy on Valhalla involves throwing the Power Drainer out the man cannon to intercept a low flying Banshee. The Power Drainer's relatively large damage radius will normally result in the disabling of the Banshee's engines for about 5 seconds, during which it can be destroyed/boarded.
 * The effects of the Power Drain can also pass through walls and floors so simply jumping to the floor on the bottom after an enemy activates one may still strip your shields through the roof if you pass through it.
 * If both Regenerator and Power Drain are deployed, your shield will be reduced even if the Regenerator is nearer.
 * When the Power Drain disables a vehicle, blue sparks can be seen on the vehicle. These sparks can also be seen when the Plasma Pistol disables a vehicle and if the affected vehicle is destroyed.
 * A Power Drain can kill any Marines inside the field.
 * Plasma Grenades can't stick to Power Drains.
 * The Power Drain can be used in a glitch called Equipment Jumping by moving you player against a wall, jumping, and then at highest point of the jump deploy the Power Drain and you will be able to jump off of it in mid air. This is a great tactic for reaching high areas of a map such as the second level of the tower on The Pit. This can also be done with the Radar Jammer and Flare
 * In Campaign, this will cause an Elite's shields to flare up, as though he was taking damage, but not a Spartan's.
 * It is possible this weapon was intended for the Elite's energy shields and the vehicles of the Covenant Separatists, since they pose a far greater threat than the UNSC forces.
 * The Power Drain can drain the shields from a Deployable Cover, but not a Bubble Shield.
 * Strangely, in Halo 3: ODST when you are in the radius of a power drain your stamina will drain, even though it's not powered by anything at all.