I would like a mob that is a moth , dark butterfly or similar to be added to Minecraft.
In future versions of Minecraft the lighting will change and this idea of mob would mean an increase in difficulty. These creepy bugs can attack you if you remove their light source ... the ideal thing is to distract them with fire or lava ... since they will be attracted by the light and die ... Their drop could be a piece of wing, but you Let make a potion with a dark effect.
Their spawn would be at night in caves and on the surface. They would be attracted by the light, to the point of accumulating a group of them and canceling the light of the torch or lighting block, creating darkness and hostile mobs could appear ... and the mechanics to avoid the these It would be convenient to put a kind of repellent like dime flower around your House or use mobs such as frogs or parrots ... making these moths fear them and not come near your house.
They could also spawn in the new Deep Dark biome, to make it more creepy and dangerous.