Perfecting the bestiary seems to me to be something that could give more complexity to the world and its creatures, as well as making it more comfortable to use.
Things like classifications, either by physical characteristics, food, behavior, habitat, intelligence, etc. The possibilities are pretty good. You could also add races and sub-races either by their powers or their birth.
They could also add depth to the world and its history by thinking of the evolutions and extinctions that creatures have had to undergo.
Perfecting the bestiary seems to me to be something that could give more complexity to the world and its creatures, as well as making it more comfortable to use.
Things like classifications, either by physical characteristics, food, behavior, habitat, intelligence, etc. The possibilities are pretty good. You could also add races and sub-races either by their powers or their birth.
They could also add depth to the world and its history by thinking of the evolutions and extinctions that creatures have had to undergo.