Oh how I hate it if you have a 95 % probability, critically fail and doom your mission. So it was great to have power over the rolls for a change. I needed a while to figure out how it works exactly. After that I was surprised by how many strategic options you actually have. Well done!
What I found missing is a display for your current shield. I don't know if this is intended but the shield seems to be effective until you cast a new one.