Kandra race, based on the Mistborn books: a shapeless or shapeshifting invertebrate that can eat and imitate creatures with skeletons by “wearing” their bones. Would have the following properties:

• When you eat a bony corpse as a kandra, you are given the opportunity to turn into that monster.
• You might otherwise have the opportunity to digest the flesh but keep the skeleton (which would be a new item using corpsenm to track which monster species it’s a skeleton of) in order to wear it later. Skeletons would have to be heavy or bulky enough so that carrying lots of them around wouldn’t be feasible, and potentially corpses should rot into skeletons instead of completely vanishing.
• You can only achieve a perfect imitation of a monster by eating its fresh corpse. Wearing a skeleton at any other point results in a poorer imitation that would be penalized in some way: it could deal less damage, have terrible Charisma, and so on.
• When perfectly imitating a monster, other monsters might not attack you.
• Eating and replicating a corpse also takes time, which would be implemented as an occupation. If interrupted, your new form is imperfect. Possibly, the time needed to assume a shape from a skeleton decreases as you get more experienced and gain more levels.
• You can exist without any bones, but this means you are a weak, slow ooze monster (perhaps kandra should be in the “b” class).
• Hunger might not work the same way. Kandra in Mistborn do not need to eat, but for gameplay balance there should probably still be some need to keep seeking out food.
• Might be able to store some smaller items inside your body, protecting them from theft, damage, and destruction.
• Can pick locks with your “hands” by selecting “-“ as a lockpicking implement.
• Sources of acid would be especially damaging.
• These are a lot of advantages with few disadvantages; some special disadvantages might need to be created, such as certain types of elemental damage disrupting your body and forcing you to drop your skeleton.
• The system of Blessings in Mistborn (two magical spikes which all kandra must keep within their body at all times) could be used. Somehow losing the Blessings would be an instadeath.

Gelatinous ice cubes, which work mostly like gelatinous cubes but also have a cold attack.

When attacking certain amorphous monsters (could be just puddings and gelatinous cubes, but also maybe jellies and other blobs) in melee, it is possible for your weapon to get stuck in the monster, yanking it out of your possession and putting it in the monster’s inventory. Unless, of course, the weapon is cursed.

A b-class monster which is a shapechanger and may transform into any P, b or j monster.

Merge the P and b monster classes, on the grounds that puddings and blobs are both classes of amorphous monsters that are sparsely populated. (Some attempts have been made to also merge the j monster class in.)

New monster: green cube, which combines the abilities of a green slime and gelatinous cube: both sliming and paralysis.