To use power drains effectively, you need to know how what they do and how big an area they affect. Power drains are a piece of equipment which you can use in both the Halo 3 campaign and multiplayer, so work the same way as bubble shields and the like. Walk over an unarmed power drain to pick it up and press X on your Xbox 360 controller to use it. When activated, it emits a shield-draining energy which effects anyone caught in its' radius, and lasts for approximately 6.5 seconds. In addition, the explosion when it over-charges and is destroyed, can in some cases kill nearby enemies.;
, Most maps have default-spawning power drains, such as Construct, The Pit and Valhalla, but they can be bought and placed on any map when editing in Forge, so use them as much as possible. Try to see the best strategies are for certain maps and what uses the power drain can perform.
 The power drain is most effective when deployed, drains your opponent's shields and is then followed by a weapon such as a battle rifle, carbine or magnum. One head shot from any of these will finish off any opponent affected by the power drain, and this is especially useful when firing upon lots of enemies bunched close together.
 Power drains are one of the most effective ways to disable enemy vehicles. When deployed, the power drain will stall any vehicle its' drain effect touches in the same way as an over-charged plasma pistol. Although the vehicle's guns will still work, the occupants and the vehicle itself will be vulnerable to a grenade or weapons fire, or if you wish, to boarding. The effect won't last long, so be ready.
 Power drains are very useful for covering areas and buying you time. If a large group of enemies are flanking you through a corridor or other area, consider throwing a power drain their way to hold them off while you make your escape. Usually, opponents who see that a power drain has been deployed will avoid the area for a while, making them excellent for holding of vital weapon spawns and areas on the map.
 Opponent in a bubble shield or regenerator? No problem! Power drains can be thrown inside bubble shields and negate the effects of a regenerator, even reducing player's shields if they are next to one. Power drains are also effective against players who have picked up over-shields or invisibility, reducing their shields and making them visible to others. And of course, nothing scares campers more than a power drains followed by a grenade.
 On odd occasions, the power drain can actually kill opponents. If their shields have been depleted and they are standing directly next to the power drain as it over-charges and is destroyed, then there is a chance that the player will die. This chance is greatly increased when the power drain is deployed near fusion coils.
 Power drains are deadly when thrown into a man-cannon, especially when it's in the path of an oncoming banshee or vehicle. Power drains are also incredibly useful when used on maps with elevators, such as Construct, where a power drain can doom anyone traveling up the lift, or be used to clear it to make way for team mates. In addition, power drains can effect players through walls and on different levels, so on multi-story levels don't underestimate them.
Learn the capabilities of power drains and how to use them.
Experiment using the power drain in a custom game or Forge.
Use the power drain in combination with other weapons.
Use power drains against enemy vehicles.
Be tactical.
Use power drains to eliminate troublesome players.
Kill players with the power drain.
Exploit features of the map.
{"src": "wikihow-all_test", "title": "How to Use Power Drains Effectively in Halo 3"}