The Metamorphica is a free download and inexpensive book that has over 650 mutations in generic format, most of which I will be ignoring in this post. An idea I got recently is so simple, yet can result in a wide array of monsters in appearance (and possibly gaining new mundane powers). For example, take a base animal, such as a lion, and roll 3 to 5 times on the Body: Form chart in The Metamorphica. The first roll is used as is and the subsequent rolls only apply to a specific body part of the creature. This lion gets horns and then anthropomorphic animal, bristles and twisted frame. Using some creativity, this is what I came up with: a lion with horns that have the shape of humanoid lions and its malformed tail is covered in hairs much like its wiskers and allow it to sense motion behind itself. The wizard was attempting to enhance its senses and the tail was the unfortunate target of that part of the process. The horns are meant to represent the crest of the wizard's house and sort of look like it. With some refinement, the bristles may spread to the mane to allow the animal to sense motion beside it as well and the tail, if not returned to normal, may be reshaped into something more useful like a toxic club or independent limb (still with the wiskers).

Of course there are several entries that may need to be rerolled- how does one apply long neck to skin, tails, horns or wings? But doing this, be it with The Metamorphica or charts of your own creation, will allow for quick and easy creation of many, many critters. I find that it is handy for the New Body Parts mutation in Gamma World and Aberrant Form (xenomorphism) mutation in Mutant Future and in addition to the mutations chart in The Complete Vivimancer.