Transformation is the art of permanently becoming something else, or of making someone else something else. Both Death and Nature Mages can do both of these, but the transformations of death are far more permanent. Transformation resets the Age of the subject, and it may heal afflictions.

Only those with living, physical bodies may be transformed. This excludes the Undead (and Demons), the Inanimate, Spiritforms, and Illusions.

There are two Death rituals that transform the user. Twiceborn and Lichcraft. Neither can be used by Plants, nor by Pretender Gods or Prophets. The resulting form is Undead, so the user cannot transform again afterwards. Both of these spells have their own pages.

The only Nature ritual for transformation is Transformation. This one has a random result, though the result is almost always living.

Whatever Transformation actually does, though, is up for debate with the new game release.

• There's an (80 + Luck)% chance that you become something neat. If you're casting this Underwater, this form is guaranteed to have an Underwater Trait, typically Aquatic.
• If you fail at this, you become an abomination of sorts. Most of these sorts of things are Mindless in that their brains are far too small, thus resulting in leaving the caster without their magic levels. If the caster has more than 4 magic levels in a single path ("god-like" skill), though, their magic is strong enough to exist without a mind; thus, they don't lose their magic levels. Their levels are also saved if they have least 3 or 3.
• The "neat" result can be an odd humanoid (from a certain list), a monster (from a certain list), or an animal. Some of these are aligned towards certain magic paths, so there is a percent chance per form that you get a level in that path. This chance in-turn has a multiplier, with a base of 1, and each point of Magic in the province adds 0.1 to the multiplier (while Drain subtracts 0.1). Every 100% on the chance is lobbed off and considered a guaranteed +1 in that path.

• There's an (80 + Luck)% chance that you become something neat. If you're casting this Underwater, this form is guaranteed to have an Underwater Trait, typically Aquatic.
• If you fail that first chance, there's an (80 + Luck)% chance that you become an abomination of sorts. This step is completely botched. The magic skill loss also applied to the non-Mindless forms, In fact, it's ONLY applied to the non-Mindless forms; this is because it's implemented by adding the Feebleminded trait, which the Mindless forms cannot have. The "minimum skill level to retain magic" is also completely botched, treated as a level cap: a fellow who transforms into a Mindless form will have AT MOST 3 in Astral and/or Nature, and AT MOST 4 in the other levels. This at least makes more sense than the other coding hiccup, but it flies completely in the face of the spell description.
• If you fail both of these chances, the abominable form you transform into is also dead. Extra Lives on the caster will save you, but you'll still be an abomination, and you'll still be Feebleminded (and/or level-capped).
• The "neat" result can be an odd humanoid (from a certain list), a monster (from a certain list), or an animal (from a certain list). Some of these are aligned towards certain magic paths, so there is a percent chance per form that you get a level in that path. This chance in-turn has a multiplier, with a base of 1, and each point of Magic in the province adds 0.1 to the multiplier (while Drain subtracts 0.1). Every 100% on the chance is lobbed off and considered a guaranteed +1 in that path.

It is not sure if Dominions 6 implements Transformation the way the spell description describes it. The list of forms that one can Transform into, good and bad, does not appear in the Dominions 6 Mod Inspector. The Pretender God/Prophet bans on Twiceborn and Lichcraft are new to Dominions 6, so the code for Transformation may have been changed as well.

Two items, the Lycanthropos' Amulet and the Pebble Skin Suit, will eventually transform their wearers. The former has a 2% chance to make you a Werewolf each turn, while the latter has a 2% chance to make you a Troll. Getting either of these may happen involuntarily, since they're cursed items, so this might not be voluntary self-transformation.

There is one Death ritual that transforms others, the Ritual of Rebirth, which turns a fella into a Mummy. It does work on the Undead, unlike other Transformations; however, the subject has to be already dead. You may also use this on someone more than once to resurrect them again, but the mechanics of that will be covered below.

There are two combat spells that transform others: these are Curse of the Frog Prince and Polymorph. The former makes someone a Frog (one of those Mindless bad results mentioned under Transformation above), while the latter turns many people into Boars.

Resummoning a specific unit (i.e. Recalling a Pretender God) transforms them back into their original form. The only exception is the Ritual of Rebirth, which summons the fellow back specifically as a Mummy.