This is incredibly fun.
Bug report: normally, you have to select dice before rerolling to reroll those dice. So, naturally, I assumed that if I selected no dice, I could hit reroll to use a reroll without rolling any dice. I wanted to do this to use the skull whose condition is “use at least three rerolls”. As a result, I rolled away a five-of-a-kind.
I can understand not wanting to make it easy to accidentally use up a reroll to no effect. However, there’s a legitimate gameplay reason to do so. So, maybe prompt “really use a reroll without rolling any dice?” and let the user do it?