10 Rules for Beginner Mapmakers

Does anyone know how to create your own heroes, monsters, etc.? If it's even possible... There was some kind of "time market" in one of the maps, which really interested me... It seems to be the author's creation... Can you tell me how these are made?...
By the way, Predvestnik posted a map called "Baikal" here... In short, I was very pleased with the cows in the meadow! Well, not really cows, but mighty gorgons!) ...