This is the creature schtick transformation, Feng Shui, p 128.

Transformation lets you change into alternate forms; human animal, some other type of supernatural creature, or even an object such as mist, a rock, a tree, a table, an elevator, or a motorcycle. General rules for most transformations are given here; each type of form is detailed below.

You may assign different attributes to each form you take. Use your base attributes and assign the attribute points differently for each form. Your total attribute points must remain the same. If you improve your attributes with experience points in the course of play all of your various forms' attribute's are altered by the same amount.

Option: If you choose to give your transformed self different attributes your transformations are more lengthy and painful than the norm: you suffer 1 point of Impairment for one sequence per changed attribute after you transformation.

Transformations are not illusory; you really change. When you become a human, your perceptions, tastes and natural behavior becomes human; the same applies when you become an animal or a monster. You must roleplay this, but it also makes the disguise very hard to penetrate. There is usually no way to do it, though sorcery Divination or Summoning, as well as a few other schticks, may perceive your true form.

Hybrid Forms

You always return to your normal form whenever you make a Creature Power check. If you spend an additional schtick on this ability you may adopt hybrid forms halfway between your own form and that of the chosen person or object. For example, if one of your selected forms is a motorcycle you could become a motorcycle with your usual monstrous head between the handlebars. If you have the tentacles schtick the motorbike could have tentacles, and so on. You can use any Creature Powers for which you have manifested attributes without breaking your transformation. A hybrid form is always considered to be a supernatural creature, and has the drawbacks and attributes of one of your Monster Forms.

Cosmetic Change

You can vary the exact form you take; if you are (or change into) a woman, you can vary your hair color, clothing style and other features, if have the form of a motorcycle you could decide upon any brand or type when each change. You can opt to have only Cosmetic change for transformation; this changes you into variants of your base shape. f you have several distinct shapes, you will have to work out with the GM whether each of these can alter it's basic form, or if only some can do it.

Animal Form

If you become a natural animal, you gain the attributes and abilities of such an animal, but keep your own skills. You lose your Creature powers and flaws, but can use Creature Powers skill as Martial Arts. See the Transformed Animal rules for typical animal abilities. You suffer no inconvenience because your attributes change when turning into an animal. If you want an animal that is more combat-capable, create it using a new Monster Form.

Elemental Form

You may choose to change your form into some base elemental substance. Examples include mist, or water, or rock. While in elemental form, you can take no action beside hiding, sneaking and moving. You cannot attack or speak or use any skills or powers. If the elemental form can move (a rock cannot move, mist can), it moves at your normal Move. It still has your normal Dodge because you are still a supernatural creature. If the elemental form is solid, like a rock, it has armour adds equal to your Magic. If it is ephemeral, such as water or mist, it normally suffers no more than a single Wound Point from any physical attack.

Human Form

You may adopt human form at will. You need to determine any visual characteristics of the form you adopt – hair colour, height, apparent weight, facial features, and so on. You can specify clothing as a part of the human shape, if desired. When human, you cannot use any of your Creature Powers, but can use all other powers and abilities. 

Monster Form

You can change into some other supernatural creature. This allows you to rearrange your Creature Power schticks and flaws; you must specify what schticks and flaws your new form has when buying the schtick. Pick a specific supernatural creature to change into; even if you can vary your exact form through Cosmetic Change, you can never change what Creature Schticks you get, except by buying another Monster Form. It is wise to be able to transformation back; otherwise you've just suffered a permanent metamorphosis. You can never go into Hybrid monster forms.

Object Form

If you become an object, you gain all the usual abilities of that object. Your GM has final say on what the usual abilities of any object might be. You keep your own skills, but cannot use any skill that requires limbs except for Dodge, your supernatural abilities still protect you.