Energy ball

The power to throw Energy Balls is an offensive ability used by primarily Demons, and in some cases Witches, Whitelighters and Warlocks. The user can form balls of energy, which resemble electrical discharges, in their hand, and throw them at targets with varying levels of voltage. They can also dissipate and control the energy ball while still in their hand.

History
Inspector Rodriguez is the first evil being the Charmed Ones encounter with this power. Belthazor also possessed this particular power, as do several other demons such as Zotars, a breed of demonic bounty hunters ("Déjà Vu All Over Again",  "Sleuthing with the Enemy") . It is a common, deadly, and effective power, worthy of frequent use in the Demonic Community.

Later in the series, some witches are shown to possess this power, notably the morally ambiguous Montana and Callaway families, Bianca and other Phoenix witches. While usually blue, some demons have shown to create red energy balls ("Bite Me", "Soul Survivor"). Cole once created a huge, powerful energy ball, with which he attempted to vanquish the Source, but instead killed the Oracle ("Brain Drain"). Darklighters and evil witches with Darklighter ancestry also seem to have this power.

Energy balls appear to be able to be deflected using mirrors, as seen when Cole tries to commit suicide, he throws an energy ball at a mirror, which rebounds and hits him, setting him on fire ("Y Tu Mummy Tambien"). Energy balls seem to be deflected by hard durable objects. Once when the Charmed Ones were being faced by three demons with energy balls, Phoebe hit an energy ball with a crowbar, baseball style, and sent it back towards the demons, effectively vanquishing them ("There's Something About Leo"). However, cars and other technology can catch on fire, explode, when hit by an energy ball.

Strength and Control
The power of an energy ball varies as it depends on the user. For instance, a low-level demon with this power would probably have to use multiple energy balls to vanquish a target, while an upper-level demon such as Belthazor would be able to vanquish a target in one hit. Users can nearly always be vanquished by their own energy balls because they are as powerful as they are.

Some especially powerful demons can kill or incapacitate multiple targets with a single energy ball. For instance, Cole once knocked Piper, Paige and Leo to the ground (and knocked out Piper and Leo) with one energy ball. Barbas, after having stolen Cole's powers from the Demonic Wasteland, threw an energy ball at Phoebe, which missed and vanquished multiple demons in a single hit. Also, some demons can throw reduced-voltage energy balls that can merely stun targets.

In "Death Takes A Halliwell", Cole throws an energy ball and it splits in two, heading towards the two Seekers. So Energy Balls can be linked to the mind of the bearer.

Some Whitelighters are able to create low-voltage energy balls that are harmless and use them to train with their charges ("Power Outage", "Blinded by the Whitelighter"). This is possibly a sub-power of their Photokinesis.

Resistance
Energy balls are usually lethal, as is the case with mortals and weak magical beings. However, some demons are powerful enough that they can withstand the blast. Also, the Charmed Ones eventually grew powerful enough that they could withstand being hit by them. The strength of the ball itself is also a factor as not all energy balls are intended to kill.