She is a big black spider with golden front legs and a purple bottom. She has a crown made with green leaves and an orange flower. She is standing on small green eggs.
The description of her challenge is:
How dare you touch her children? You could've killed one! Get ready to taste Spider Mamaw's venom.
Her regular challenge requires 75 Pygmy deaths within two days.
If you defeat Spider Mamaw, you will get her idol. The idol look exactly the same to Spider Mamaw except the color. When turned on, the eggs on the floor will glow with a green color. This idol more experience when sacrificing pygmies.