Chance roll
Sometimes you will need to decide an outcome by pure chance, i.e. without taking into account your skills or the skills of your enemies.
If you roll the same or more, it means success, or that the effect occurred.
Example
A werewolf bite means a 2d6 / 10 chance that the character gets infected and becomes a werewolf.
If the GM rolls 10 or more, the character is infected. So a successful chance roll is not always favorable.