How the calderon works? I mean, i don't know how to use it and i don't know how it works and what will do in the future.

Cauldron is not finished yet but how it will work is. You have to place it in the ghost room. Bring 3 ingredients and drop them in the cauldron. If done correctly it will make a dagger that can deal with that ghost. Each ghost weakness will be mentioned in the ghost pedia. And you have to find recipes in different map section so it will appear next time hover your mouse on it.