Hardin:
The ability to change the soul and then restore it to its original state is an essential condition for transformation magic.
If the soul perishes after transformation, or if the subject cannot be returned to its original state, the power is worthless.
Needless to say, this posed an extremely difficult problem even for my intellect, but I was able to use Mimir's Elixir and principles of Necromancy to solve it.
Still, the process has not been perfected...
I am now experimenting with a method that I believe may provide that last key.
By using Mimir's Elixir and the Stabilized Ectoplasm that you brought me, I am reasonably certain that I can allow your soul to endure the transformation process.
Once in that state of transformation, you should be able to use the Seal of Transformation to further transform at will.
Seal of Transformation?