From Halopedia, the Halo wiki
- This equipment will stall a vehicle's engine, but the weapon(s) on the vehicle still work. The most effective way to take out an armored vehicle such as a Warthog is to throw a Power Drain followed by a grenade, killing most of the players on board. Several follow-up shots will take out any survivors.
- The Power Drain is highly effective when used in conjunction with headshot-capable weapons such as the Battle Rifle, Carbine and Magnum.
- This piece of equipment is useful when facing multiple enemies; once their shields are depleted, the group becomes significantly more vulnerable.
- As the Power Drain can pass through the Bubble Shield, it's a good idea to throw one inside of a Bubble Shield while your enemies are inside of it.
- If a 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 easy targets.
- Deploying this equipment near a popular sniper position or an area where people land after using a Man Cannon can make your enemies susceptible to surprise attacks.
- It is best to keep at a distance from an enemy with a Power Drain, because it is only effective at close range.
- The power drain is a useful for of hijacking an enemy vehicle. For example, if you can throw one at a Warthog or Zurdo-pattern Wraith, it will immobilize them and deplete their shields, meaning that hijacking will kill them and gain you a vehicle. Also, if a Banshee is close to the ground, a power drain can force it down and allow you to skyjack it.
- The Power Drain negates the effects of a regenerator, rendering it useless.