Okay, firstly, I've been away from Tumblr for far too long...time to fix that...
This if my first foray into electronics for a couple of years and I love how the likes of the Raspberry Pi have made miniaturised control easily available.
I put together the glowing orb in this video for a cosplay project, with the "pulse" effect being provided by a Arduino-compatible Pro Micro board from Sparkfun. The code for making the effect is about 15 lines long and includes a randomiser to change the timing between each "pulse" and give it a more random, organic feel (which you would expect a magic orb to have).
Power requirements seem to be minimal, with the unit happy to take power from a USB battery pack via the onboard micro-USB port, and also includes a regulator to accept juice from any other source between 5v and 12v.
Gonna be using some more of these bad boys in my costumes!!!