This is a very simple brush i made some time ago, while it is called "Cloud Brush" because it is very good for, well you guessed it painting clouds, it is also great for just blending or painting other materials such as fur or leaves.
This brush is configured so the more you press the more it adds color and disperses the texture, and on light presses just blends.
There are two versions,"Large dispersion" and "Small dipsersion". These are basically the same only they have different dispersion values, and I do recommend you play with the dispersion parameter to get the most out of this brush.
Keep in mind this uses the Color Smudge mode so it does have a quite an impact on performance, if you have a low end PC try to use it at a small size.
How to install: Simply open Krita's ressource panel (Settings>Manage ressources) and when the window opens click the "import brushes" button. Select the .bundle file, and now they should display in your brush panel.