Generally, when a hero is subject to an unusual or magical attack, he or she gets a saving throw to avoid or reduce the effect. Like an
attack roll, a saving throw is a 1d20 roll plus a bonus based on the hero's class and level (the hero's base save bonus) and an
ability modifier.
A natural 1 (the d20 comes up 1) on a saving throw is always a failure. A natural 20 (the d20 comes up 20) is always a success.
Reflex: These saves test the character's ability to
dodge massive attacks such as explosions or car wrecks. (Often, when
damage is inevitable, the character gets to make a
Reflex save to take only half
damage.) Apply the character's
Dexterity modifier to his or her
Reflex saving throws.