I've been playing Minecraft again lately, and one of the more complex mechanics is around enchanting tools and armor. The order in which you apply and combine enchanting books can be the different between costing 20 levels, and being too expensive to even complete. There's a hidden formula (the prior work penalty) that goes into it. I was looking to see if anyone had built a tool to solve it for you, but I just found other people asking the same question. So I created one.