Okay... here's what you do.
http://www.rainbowsymphonystore.com/plasmaball360.html8 " plasma ball... okay.. that's the easy part... finding the large size plasma balls.
Next .. the electronics for them would have to be in the shaft of the staff...
Okay.. now the tricky part...
Since these sorts of things use DC power (hence the power supplies that generally plug into your 120 V 60 hz AC outlets. That said batteries can be used... by hooking them up in combinations of series and parallel configs (to boost longevity of the batteries and reduce the load on each individual battery. I'm betting the power supply is something 9V with an amperage rating you can look up. The trick then is to just do a little math, and pull out a digital multimeter and measure the resistance of the circuitry itself so you know how much resistance you need to overcome to get the amperage rating you need to energize the spheres.
Taking a college course in basic DC and AC circuit networks will give you all you need to do this. I just took my 400 level classes in this for my engineering degree (just went back to finish my degree this last year) and it's not really as bad as you might think.
Baring this... get a Schaum's outline book (cost you 19.00 at a bookstore) on basic electric cirtuits will give you all the tools you need to do this.
If it's a 9 V power supply.. you can do this with a buncha 9 volt batteries and put them in the shaft and head of the keystaff. it'll even add weight to the thing.
Hey.. if you do it... you should give Jenny a call and see if she'll break out the ultimate ifurita costume and dress up with the staff at some point. I think everyone who is an elhazard fan know's Jenny's ifurita outfit.
If you need specifics though... as in you need some help with the voltages and such... drop me a line.. I'll see what I can do... provided you have at least put some effort into figuring it out yourself first. The thing is... if you haven't tried.. then most of what I'd say would be greek to you right off the bat... and it'd be like trying to explain how to drive stick shift to someone that has never seen a car in their life.
The point is, you need to have the plasma balls on hand, or know what their amperage ratings and voltages are.
Here is why.
Since the plasma balls operate on DC current, you typically are using a step down transformer(depending on the voltage requirement), a voltage rectifier and a couple other devices in the powersupply to give you a nice steady (single direction) current. Now, current (amperage) is defined as the Voltage divided by the resistance.
So.... if you have a 120 V voltage source with a 100 ohm resistance, you get a 1.2 amp current.
Now, with the DC powersupply, you have two leads.. a positive lead, and a ground. So, what this means if that you -can- substitute batteries for the normally hooked up power supply by wiring the positive terminal lead of your battery supply to the postive lead of the plasma ball, and hooking the ground to your battery supply. Note I said SUPPLY, that's because you'll be hooking up some batteries (more than one) in parallel, and some in series... so that the load you need to create will be distributed across them. You'd also need to include an appropriate resistor (after accounting for the internal resistance of the batteries) so get your current right.
The one thing is... can you read schematics?... I hope so, because otherwise it's hard to explain to someone what exactly they'd need to do.