View source for Criticals and Fumbles (Saves)

Criticals and Fumbles occurr when the dice comes up with an extreme result, 1 or 20.

==Fumbles==
A roll of 1 is considered a Fumble. This means that, almost always, the Save has failed.

If a roll of 1 would have succeeded (due to modifiers), make a new Saving Throw with -20. If this Save would be successful after this, consider it a Glancing Hit - otherwise, it is a failure. If the character would be incapable of this on a re-roll, they do not make a new roll - it is a Failure. A re-roll from a Fumble cannot be a Critical.

==Critical==
A roll of 20 is considered a Critical, meaning the character is almost always safe.

If the Save would have been a failure or a Glancing Hit, increase the effective roll by 10. If this would still be a Glancing Hit, it is considered a Success instead. If it would still be a Failure, consider it a Glancing Hit instead.