Many adventuring groups enjoy and celebrate those moments when the dice roll their extreme values.
As an option, rolling 2d6-2d6 and scoring a +10 as the white dice come up sixes and the red dice come up ones can count as an automatic success regardless of the penalties stacked against the Adventurer.
If the roll resolved an attack, then the attack scored a critical hit on the opponent doing an extraordinary amount of damage, usually doubling the expected amount.
However, if used, these optional guidelines also apply in the negative direction.
Rolling 2d6-2d6 and scoring a -10 as the white dice come up ones and the red dice come up sixes counts as an automatic failure regardless of the bonuses stacked in favor of the Adventurer.
If the roll resolved an attack, then the attack scored a critical miss, also known as a fumble, resulting in a catastrophically unwelcome outcome.
Traditionally, a fumble described when a sword-wielder lost their grip on their weapon itself, suddenly disarmed in the heat of the battle.