Taken with a Nikon D3s, 85mm f/1.8 prime, and Four Sb-900s.

The first is in a softbox overhead of the hand. (Set to manual, around 1/2 power with minor adjustments made during the whole process.)

The next is in a mini-softbox to camera right at about a 45 degree angle. (Set to manual, around 1/2 power with minor adjustments made during the whole process.)

The third is on the floor directly behind the hand (Set to manual, around 1/2 power with minor adjustments made during the whole process.)

The fourth acted as the commander.

Shutter speed: 1/250th
f/13
ISO: 500

It took a while for me to figure it out, but in order to make this shot work you have to keep TTL out of the equation that way it saved me the minuscule amount of time where the bubble would completely disappear.. I did this by switching to manual, then it was all about patience.