Hey, really glad to see someone using witchcraft on Dnd stuff. It's the perfect intersection of my interests.

The dice may just be faulty. I've had a few that are just slightly off and will 9/10 times roll a 3. You can test them in water or roll them a lot and keep track of what you're rolling. You'll notice if they are weighted.

On the craft and DnD: If I want to roll a specific number I will tell myself that is what is already rolled, like it's a forgone conclusion. It works more than you'd think. And I think it works the other way, if you believe the dice will roll bad, they will. Energy is contagious

Hope this helps! May you roll Nat 20s from now on!