![](https://i.imgur.com/JRsfE0i.png)
Yep, the other dice are used mostly for damage or, for example, rolling how many brownies show up.
D20 is usually rolled to check for success or failure. 1 is critical failure and 20 is critical success so the effects are usually doubled. For example on a 1 the brownies mess up your entire room instead. On a 20 they vacuum, dry clean all the sheets, fix up everything, and the place is basically spotless.
If you beat the number I gave, its just a normal success. If you don't, nothing happens.