A permanent transformation is a transformation that cannot be easily undone, if at all. While the vast majority of transformations are freely swappable throughout the game, body parts affected by a permanent transformation will simply fail to be affected by any transformative items the player uses. The decision to undergo a permanent transformation should always be highlighted to the player, with little doubt as to the consequences; it should never be something forced or untelegraphed.
Unlike normal transformations, which are mostly purely cosmetic, permanent transformations can grant base attribute changes (either up or down), perks, and powers. They are also likely to be significant in various storylines.
Permanent transformations come in three levels:
Level 1: Powerful alchemical concoctions. The Fantasy Treatment might quality for this.
Level 2: Potent curses and magic. Lady Oxana Evergreen's tanuki curse is one of these.
Level 3: Divine intervention. Choosing to become a kitsune (Keros), an ent (Velun), a valkyrie (Lumia), etc all count for this. The process always involves selling off your soul, so you cannot pledge yourself to two deities at once.
A permanent transformation can only be undone by one of a higher level, which replaces the previous one. Hence, care and consideration should be taken when choosing to partake of a permanent transformation.