From the publisher:
Our new Skillscape system, we believe, adds something new to gaming. All systems in Chivalry & Sorcery are based upon it, combat, magic, and, of course, the skills. Results are obtained quickly and easily by rolling a percentage pair (1D100%) and a third D10 of a different color, known as the Crit Die.
Success or failure in performing some task is determined by rolling the percentage pair against the character's success chances for that particular task. The Crit Die determines how well the character succeeds in his task. It may also determine how badly he fails. In Combat or Magic, the Crit Die determines how much extra damage is done and also determines whether or not a Critical Result has occurred. In Skillscape, many of our skills have Crit Tables which tell the degree of success (or failure) one has with his Critical Result. It's fast, simple, and easy!