Free version of Erosion Brush tool. It does not have an erosion painting mode, in other aspects, there is no difference.

This script is targeted not to make the terrain of your dreams in one click, but to provide the artist with a handy and useful tool. It gives an artist the ability to modify terrain to make it realistically rough in the places where it is really needed to, leaving all the others untouched. Terrain is edited in Unity without using third-party standalone toolkit; not before creating a location, but while working on it - all this gives the level artist a chance to create amazingly looking scene in a very efficient way.