Text Anagram Animation in After Effects
It's difficult to give advice on how to achieve this effect without knowing what knowledge you have in animation and motion graphics. In on itself, this is a very easy animation which will take up to 5 to 6 hours of work.


Create the letters individually in a compositing program like After Effects or Nuke
(optional) make the letters emit particles to make it look like actual embers, using something like trapcode particular and setting the emitter type to layer, then selecting the text layer.
Use glow, turbulent displacement, displace and fractal noise to your liking until you're happy with the result.
Turn the layers into 3D-Layers so you can rotate and move them on each axis.
Animate them using keyframes so they move according to your needs.


The hardest part in getting these things right is the lighting on the set. If you're filming in a dark area, these letters would emit a lot of light, which you would see on other actors and the environment. Try lighting the set accordingly while shooting, otherwise you would have to resort to lighting up the footage in post, which will not look as good as doing it for real.