Well, let's look at your build.

You're running 8 beam arrays. Each of those probably has "to self: -10 Weapon Power when firing other weapons" on the tooltip, right? So your power drain should look like this if all weapons are firing:

First weapon: no power drain, total of 125

Second weapon: -10 power, total of 115

Third weapon: -10 power, total of 105

Fourth weapon: -10 power, total of 95

Fifth weapon: -10 power, total of 85

Sixth weapon: -10 power, total of 75

Seventh weapon: -10 power, total of 65

Eighth weapon: -10 power, total of 55

Okay, great... so if you fire all 8 beam arrays at once, you should drop to around 55 / 125. This is logical because beam arrays are energy weapons, and thus require energy. The more weapons, the more energy required.

Now, enter Beam: Fire at Will. For every beam array, you fire one beam at your target, and a second beam at a random target. This second beam is technically a separate weapon, so your power consumption is doubled. Now multiply that by 8. So with Beam: Fire at Will, your power consumption will look like this:

First weapon: no power drain, total of 125

- Secondary beam: -10 power, total of 115

Second weapon: -10 power, total of 105

- Secondary beam: -10 power, total of 95

Third weapon: -10 power, total of 85

- Secondary beam: -10 power, total of 75

Fourth weapon: -10 power, total of 65

- Secondary beam: -10 power, total of 55

Fifth weapon: -10 power, total of 45

- Secondary beam: -10 power, total of 35

Sixth weapon: -10 power, total of 25

- Secondary beam: -10 power, total of 15

Seventh weapon: -10 power, total of 5

- Secondary beam: -10 power, total of -15

Eighth weapon: -10 power, total of -25

- Secondary beam: -10 power, total of -35

Of course, since you can't actually have negative power, those last 3 beams just won't fire, or won't have any damage. Also, the drain of each beam only takes effect if the beam actually fires. But yes, if you try to fire 16 beams at once, you will run out of power.

please note, this post is entirely based on the assumption that fire at will doubles power use. I have not actually tested this, but you can by turning half your weapons off and seeing if your power still drops completely, or only drops to "normal" levels.

I still want bare feet....

**on ALL costumes.**