You get a Metamorph when you fuck up making a Chimera.
The different body parts reject each other. Instead of forming one cohesive crossbreed, they form a black ooze which shape shifts between different forms. The Metamorph is uncomfortable in all of its bodies, switching between them and its abilities at will- it can be a slime, a dog, a man with weapon created from ooze, all within a few moments of each other. The Metamorph is more like a violent, bloodthirsty shapeshifter then a living creature; and it only “lives” for a few hours once created as its lack of stability causes its death.
To create a Metamorph on purpose requires a specific process, and several body parts and samples from multiple creatures. They are then placed in a large cylinder filled with several dangerous and very expensive alchemical agents; such as Thaumetic Sulphite and Voltaxic Sulphite, and heated to cause a powerful reaction. Because of the fact that Metamorphs lash out at every living thing they see and will always attempt to kill their makers; the concept of creating one except as a trap seems daft. Even in the short period that it is alive, especially during its gestation process in the tube, the Metamorph can create several rare or potent thaumaturgical compounds and alchemical reagents- things that cannot be created in a test tube by require a living belly to stew. Imagine combining the potency of a dragon's body with the healing properties of a unicorn- but you will have to content with a powerful foe to take it.
Each part of the metamorph, parts of the living things put into its vial, determine its capabilities. Note that this isn't a realistic depiction of a chimera; behaviors aren't just altered by the brains, it is all organs. This is magical thinking that powers our fantasy world. The metamorph with a liver of a pig, the stomach of a sheep, and heart of a lion will sweat and smell like a pig, want to eat grass, and have a warriors heart of a lion, and so on. If any primary body part is mixed, use the one that is most prevalent or comes from the creature with the most HD, which is dominant over the other body parts.
Metamorph Generator Tables
All Metamorphs start with 8 HD, 14 AC, and 14 morale. It lives for 4+1d4 Hours.
The Vitae is the primary liquid biomass placed in the contained.
Hot Blood, from mammals and birds, adds +2 to hit
Cold Blood, such as from reptiles, add +2 AC
Insect Ichor adds +2 to saves and poison to its attack
Plant Sap adds +1 HD to the Metamorph
Black Blood of a monster or living-dead make it immune to all 1st level spells.
Gel or Slime Ooze make the creature immune to acid and gain an extra 1d4 acid attack.
The Organs determine the Metamorph's behaviors and attacks.
Predator Organs make the morph attack with a deadly pounce; dealing 2d8 damage on a hit.
Prey Organs make the metamorph attack in self defensive desperation; two attacks at 2d4 on a hit.
Organs of Intelligent creatures make the metamorph attack with precision. Deals 2d6 with +3 to hit.
Abomination organs makes the metamorph attack with a random elemental blast at 2d10, but -2 to hit as it is blasted out of an unidentifiable orifice.
The Structural body parts put into place changes the Metamorph's form and speed.
Bones grant the Metamorph more speed and weight. Always goes first.
Shells of insects or crustaceans give the metamorph average speed, but +2 AC
Fibrous structures such as from jellyfish or only leather/skin placed within; the Metamorph goes at a normal speed but can squeeze its body through any gap.
Dried Wood makes the Metamorph more plant like. Rooted in place, adds +2 HD, goes last in each combat round. No weakness to fire; it's made of goo and ichor.
The Eyes determine the Metamorph senses and magic.
Bird's Eyes grant incredible vision. +2 to hit and ranged attacks; goo bow or evil spit.
Beast Eyes grant +1 morale and the Metamorph can track through brush.
Fish Eyes are unblinking, lidless. Metamorph cannot be surprised. Casts Hold Person once p round.
Man's Eyes are full of desire. Can read and knows two random 1st level spells, casts them once p day.
Monster Eyes glow in the dark. Will lead party members into traps or other monster ambushes.
Why Make these things at All? - Roll 1d4
 Metamorph's ooze can be sieved and boiled to produce 2d10+10 healing potions.
 Chemical processes within the Metamorph create 2d6 random gemstones as waste products.
 Studying the body of the creature unlocks secret knowledge of life. What makes you, you?
 Metamorph is born in a “dormant” state. First sample of blood or hair given to it; it will hunt and kill whoever the sample belongs to.