It's a fantasy role-playing game.

DM: You are Vax Vax'ildan, a half-elf rogue . You are the member of the famous group of adventurers. Previously, The frost worm bites Keyleth, who casts Blight as payback and heals herself. you asks Pike for healing, then hits the visible worm.
DM: Oh, with the disadvantage-- sorry, the second roll-- thank you for reminding me there. It would have been a 13 on the second one plus nine, that would be 20.
Player: Still hits! Uncanny Dodge please! To halve the damage.
DM: To halve the damage? Yeah, you can do that on this one. But first then there's the bite. I will do that now. That is 21 points of piercing damage?
Player: Unconscious.
DM: With it halved?
Player: 21 halved?
DM: 21 halved would put you at 11.
Player: Oh, yeah. Okay, no, I'm still on my feet.
DM: Okay.
Player: (dazed mumbling)
DM: The tail stinger's going to swing at you with disadvantage. That is 14. Rolled a six and a five. So, as the bite clamps down at you its tail tries to strike at you but misses entirely. However, its jaws attempt to close around you, I need you to go ahead and make a dexterity saving throw.
Player: Hold on. 16.
DM: 16. As you try and move out of the way, it's not quite fast enough as darkness takes you, the mouth (slam shut sound) clamps around you, (gulp noise) and you are swallowed.
