Metamorph (Alchemist Archetype)
After the druid, the (currently available) class most heavily associated with shapeshifting is perhaps the alchemist, given their mutagen and an extract list that includes almost every polymorphing spell and many others that alter them in subtler ways, either granting simple buffs or granting new, temporary abilities.
While plenty of alchemist archetypes help specialize in such form-shifting, there is one that goes further than most, unlocking the secrets of form-shifting alchemy the likes of which few have ever seen.
In short, these metamorphs have, through their strange sciences, learned to unstick their own forms, allowing them to, with a force of will, reshape themselves temporarily.
With their ability to shapeshift, these alchemists can mimic most humanoid races for hours at a time, though as they gain knowledge and power, they can later take on the forms of more monstrous humanoids, and even the forms of giants. The most powerful can shapeshift at will, though they still tire out quickly.
The drawback of this advanced research is that traditional alchemical learning lies forgotten, giving them no extracts, and no bombs and the like, though they still learn the secrets of mutagens, as well as discoveries.
Furthermore, the incredible control these alchemists have over their form allows them to alter the placement of internal organs in an emergency, helping to negate deadly blows.
Want to play a sneaky, shapeshifting character, but don’t want to wait for the shifter class, or want the sciency flavor of discoveries? This archetype can certainly provide that. Since they miss out on a lot of the major defining features of the alchemist class, one must approach them differently when building them. I definitely recommend as many discoveries that improve the mutagen as possible, including feral mutagen, as well as those that don’t rely on extracts, potions, or bombs to be of use. You could build them both as a melee tank or damage-dealer, and as a stealthy sort, using their shapeshifting to provide the perfect disguises.
Given the nature of their transformation, its safe to say that certain percentage of alchemists that become metamorphs do so by accident, their abilities being the product of an experiment gone wrong. Some might have been this close to being brute vigilantes rather than metamorphs, depending on the specifics. Regardless, they must be wary of whom they reveal their abilities to, lest they be mistaken for lycanthropes or shapeshifting monsters.
A victim of horrific experimentation, Vadu escaped into the wild, using his newfound abilities to survive. Now the orang-pendek have become something of a local legend, a small ape-man that can twist into the monstrous forms of gargoyles and trolls, and even, so they say, the form of a gigantic dinosaur man.
For years, Dr. Ekrimmon has been visiting Cliff Giants in the guise of one of their own, learning their ways, and how they connect to the land. Now, he is on the verge of a breakthrough to add elemental beings to his array of forms, but he’ll need samples from elementally charged creatures, and there’s no guarantee it will work.
Recently, reports of strange apparitions have been sighted in Orbhad, gargoyles, gnolls, and the like, all individuals, all vanishing into the streets soon after. None realize that these are all the same person, a metamorph exploring their newfound power. However, other forces in the city, both serving the law and flaunting it, have taken notice.