When you are awarded a hero point. you can immediately spend it to gain a feat (see the Feats section for more details). If you don't spend it to gain a feat, draw a hero point marker and keep it with your character until you spend it; when you spend it, return it to the box.
During a scenario, you can spend 1 hero point to reroll the dice on your check (see the Roll the Dice section for more details). After a scenario, you can spend all of your hero points (minimum 1) to return from death (see the After the Scenario section for more details). You can only spend a hero point to gain a feat when it is awarded to you.