It's a fantasy role-playing game.

DM: You are Fjord, a half-orc warlock . You are the member of the famous group of adventurers. Previously, Vera reveals herself to be a formidable mage, causing an Ice Storm which slows Nott, Caduceus, and Yasha and casting Mass Suggestion on the Guards to arrest them. you, seeing the tide turning, summons a demon onto the ship to distract the crew while rushing himself to the aid of Caleb.
DM: That's what rogues can do! Yeah, whenever you have to make a dex save against an effect, take half damage. If you succeed, you take no damage. If you fail, you take half. You should read your character sheet.
Player: Can I do fanatical focus?
DM: Yes you may.
Player: I'm going to do the fanatical focus once per day.
DM: So you get to re-roll that. Once.
Player: 19 plus two is 21.
DM: Okay, so she only takes 11. However everything in this, for the next round, is difficult terrain as there's now giant hailstones and sleet slicked all over the rickety docks.
