It's a fantasy role-playing game.

DM: You are Jester Lavorre, a tiefling cleric . You are the member of the famous group of adventurers. Previously, Caleb and the crewman make their way upstairs, fighting, and you joins in the fray as Caduceus makes it onto the boat, which still moving away from the harbor, and he drops the disguise. The crewman continues to attack as you and Caleb try to convince him to put down his weapon.
DM: Probably. All right, so on that, he's going to go ahead and make his way towards you, Jester. He comes up and is going to make two swings at you.
Player: I use Hellish Rebuke.
DM: Well, first you have to see if it hits. That is going to be a 15 to hit. I believe that misses.
Player: No.
DM: That's a 19 to hit.
Player: Okay, yes. I use Hellish Rebuke.
DM: All right, go for it. That is ten points of slashing damage to you.
Player: Okay.
DM: A two-handed (whoosh) swings past you.
Player: He takes 21 points of damage back.
DM: He has to make a save, right?
Player: Yes.
DM: That is a natural 14, but has no bonus to his dex, so it's a 14.
Player: Yeah, it's only a 12 dex save.
DM: Right, because it's a racial ability.
Player: Yeah, it's a racial ability.
DM: He takes half damage? What is it?
Player: What did I say? 21? Half of that, 11.
DM: All right. Ice shards pierce out of the blast area and his body is (groans). He's looking really hurt now, and he's frustrated and his eyes are starting to go a little wild, realizing that this is turning on him pretty heavily. All right. Caduceus. (counting) You're just like, (breathing hard). As you glance over--
