Basically the title. Low drop rates - ideally just from the specific creatures themselves. If you had each item as a random still from the creature animation you could have several different 'versions' of each item and a market based on which angle of creature people preferred. Wouldn't need to actually be a creature or anything - no combat or fighting, just an item using the creature image. Would be especially great for decorating lawns or maybe dropping around town to surprise people.
Collect the whole set today!