INSPIRATION

Inspiration is a rule the Dungeon Master can use to reward you for playing your character in a way that's true to his or her personality traits, ideal, bond, and flaw.

Heroic Inspiration

You can hold 1 Heroic Inspiration at a time. If something would give you one while you already have it, you may give it to a PC in your group who lacks it (otherwise it’s lost).

Spend it to reroll any die immediately after rolling it; you must use the new result. If you rolled with advantage/disadvantage, you may reroll only one of those dice.

Gaining it: The DM can award it for roleplay/heroics; other rules grant it (e.g., Humans get one after each Long Rest).

DM Dial: Be explicit about what earns it at your table to avoid hoarding or spam.