I keep hearing about how people have problems using things like hero editor to properly experiment with builds, so here is my Save folder that I've been using:
https://dl.orangedox.com/Savetest2.1These characters come with 200 stat points so you can test how energy scales with your spell damage. To start over, you could always re-download the folder to have 10 energy again.
One thing is I cannot add magic pierce or mastery to charms, so if you want to test that, you'll have to do it yourself with gear/diamonds/facets.
Just swap out your Save folder with this one. This contains all 7 classes at level 99 with 20 to every skill and charms that add crazy skills and stats. These characters aren't "geared" but it still really helps you get a feel for how a lot of things play out in late game.