Each biome has its local God. They are the children and followers of The Elder.

But they have wood for brains so they are afraid of fire and run like drunken sailors.

Our task is to kill the evil God of each biome and slay all the followers for their existence is what give their God substance.

After being cut off from the rest of the world tree they grew in numbers.

Basically this is what happens when you don't weed the garden.