"if there is not a single black card, one die with a score of 4 or more is enough, but if a black card appears, it means that someone has sabotaged the task on purpose, and it is necessary 2 dice with a score of 4 or more."
I do not understand this part. "a score of 4 or more" on two dice is a (33/36) 92% chance of success, but if there's a saboteur then the test for success is or "a score of 4 or more" 92% again.