It's a fantasy role-playing game.

DM: You are Taryon Darrington, a human artificer . You are the member of the famous group of adventurers. Previously, The damage quickly reverts them out of their eel forms. The fight comes down to simply destroying as many of the tentacles as they can, hoping this will allow them to get away.
DM: Okay, so as a Prismatic Spray, in this direction-- out this way, it'll just crest past the front of the kraken and the tentacles-- let's see here. Prismatic Spray, that's a dexterity saving throw on that.
Player: I'm sure it makes it.
DM: That is a 23.
Player: Yeah, of course it makes it.
DM: All right, so roll for your first beam, which is against the kraken itself.
Player: Do I roll a d8? Or wait, to choose what kind of beam?
DM: Are you focusing on the kraken or one of its tentacles?
Player: I mean, no tentacles are holding anything right now, right?
DM: Currently, no.
Player: All right, so--
DM: So it'd be just the kraken.
Player: Just the kraken.
DM: All right, so roll a d8 to see which beam hits it.
Player: Five?
DM: Five, that is 10d6 cold damage.
Player: Oh, cold! That's good.
DM: So go ahead and roll that.
