Impossible Toughness Saves

If the DC of a Toughness save is so high the character cannot possibly succeed, even with a 20 on the die roll, the Toughness save is still rolled to determine the effect (the amount the save misses the DC).
A natural roll of 20 means the character suffers only the minimal result of failing the save, regardless of the DC. Fate intervenes to spare the character from otherwise certain doom.

Impossible Toughness Saves

A Better Tomorrow Kurenen