Solo RPG Combat with an AI Dungeon Master: How the Dice Really Work (2026)

Combat is where a solo tabletop RPG either feels real or feels like a chatbot humouring you. The difference comes down to one question: who rolls the dice? This guide walks through exactly how a fight resolves in VoxDungeon, a browser game where you speak your actions aloud and an AI dungeon master narrates the result. Every mechanic below is described as it is actually built, not as a wish list.

The short answer: the AI narrates, the engine rolls

The AI dungeon master in VoxDungeon is explicitly forbidden from rolling dice. Its instructions tell it that it does not roll and must never state a die result itself. When you attempt something uncertain, such as an attack, an ability check or a saving throw, the AI instead writes a roll request: which die, what modifier, and the Difficulty Class or Armor Class it is up against.

That request goes to the game server, which rolls with a cryptographically secure random number generator. The results come back labelled as authoritative, and only then does the AI narrate what happened. It is told to treat the numbers as real and not change a single one. In practice that means a language model cannot fudge your attack, forget your bonus, or quietly decide the dragon survives because it would make a better story.

Which 5e rules the dice engine actually applies

VoxDungeon is built on the 5e System Reference Document, and the roller enforces the rules that matter most in a fight:

• Natural 20 and natural 1. A natural 20 on a d20 succeeds automatically and counts as a critical hit. A natural 1 fails automatically, no matter how high your modifier.
• Critical damage. On a crit the engine rolls the damage dice a second time and adds only the dice, not the flat modifier. That is the 5e rule, applied exactly.
• Advantage and disadvantage. When the AI calls for either, the server rolls two d20s and keeps the higher or lower one. You see both faces in the log.
• Targets. Attack rolls are compared against an Armor Class and checks against a Difficulty Class. The result is reported as a success or a failure, with the total and the target side by side.
• Damage expressions. Weapon damage is rolled from the dice on your sheet, such as 1d8+3, and your equipped weapon's dice are handed to the AI so it uses the right ones.

Up to twelve rolls can be resolved in a single turn, so a flurry of attacks or a group saving throw resolves in one pass rather than one roll per exchange.

What the character sheet tracks during a fight

The AI is handed your sheet every turn and is told the sheet is authoritative. It is instructed never to contradict it and never to invent gear, spells or resources you do not have. The sheet includes your current and maximum hit points, your Armor Class, all six ability scores, your weapon and its damage dice, armor and shield, gold, notable items, known spells and remaining spell slots. If a leveled spell has no slot left, the AI is told it cannot be cast and must say so in the fiction.

After the rolls are narrated, the AI emits structured game actions that the engine applies to your sheet: damage you took, healing, experience, gold, and items found. Damage you deal to an enemy is narration only, because the engine already resolved it. Your interface shows the hit point change, plays the matching sound, and keeps a running tally of death save successes and failures and any conditions on you.

A round of combat, step by step

Here is an illustrative exchange. The numbers are made up for the example, but the sequence is exactly how the game works.

1. You speak. "I draw my longsword and swing at the skeleton on the left."
2. The AI requests rolls. It asks for an attack at 1d20 plus your modifier against the skeleton's Armor Class, with your longsword's damage dice attached.
3. The server rolls. Say the d20 comes up 17, for a total of 22 against AC 13. That is a hit, and the damage dice land on 7.
4. The AI narrates the real result. One or two sentences, because the narration is read aloud and long text kills pacing. Then it offers you four meaningfully different choices for your next move.
5. The engine updates the sheet. If the skeleton's riposte connected, you would see the hit points come off and hear it.

If that d20 had shown a 1, the swing would have missed regardless of your bonus, and the AI would have narrated the miss. If it had shown a 20, the damage dice would have been doubled.

Combat is only one option

The AI's standing instructions say that combat is never the only path. Diplomacy, stealth, cleverness and retreat are always meant to be viable, and the four choices it offers each turn are supposed to include one bold option, one clever one, one cautious or diplomatic one, and one unexpected or risky one. If you are a wizard with two spell slots left facing six goblins, talking your way out or lighting the oil on the floor and backing out are real options the game expects you to take.

Difficulty also adapts. The AI is told to ease up subtly if you are struggling and raise the stakes if you are dominating, and to scale challenge as your character levels.

What it does not do

Honesty matters more than hype here, so a few things VoxDungeon does not have:

• No initiative tracker. There is no turn-order grid. The AI narrates who acts and when in prose, the way a theatre-of-the-mind table does. Initiative appears in your class features, such as a barbarian's advantage on initiative rolls, but the engine does not run a separate initiative round.
• No battle map. Positioning is described, not drawn. Each turn does produce a short scene description that is used for illustration, but it is a mood piece, not a tactical grid.
• No AI party members. You are a party of one. Allies you meet are NPCs the AI voices and remembers, not controllable companions with their own sheets.

Death is real

The default adventure style is an endless roguelike. The world persists and NPCs remember you, but death is permanent: when your character dies, that run is over. The AI is instructed to make death meaningful rather than cheap, and your death saves are tracked on screen so you know exactly how close you are. If you want a lighter stakes session, keep an eye on your hit points and remember that retreat is always on the menu.

Tips for fighting well by voice

• Name your target and your weapon. "I attack" is ambiguous. "I swing my longsword at the nearest goblin" gets you the right dice against the right creature.
• Use your spells on purpose. The AI knows your remaining slots. Spend them where a check would be hard, and save a slot for an escape.
• Ask for the check. If you want to kick a table over to block a doorway, say so. Uncertain actions get rolled, and creative ones are explicitly meant to be rewarded.
• Read the roll log. Every result shows the notation, the natural roll, the total and the target. If a fight feels unfair, the numbers are right there.
• Typing works too. Voice is the headline feature, but you can type your actions if you are somewhere you cannot speak.

How to try it

VoxDungeon runs in any modern browser with nothing to install. The free tier includes 5 adventures per day at up to 50 turns each, with voice input and the full narrator cast. Premium is $4.99 a month and unlocks unlimited adventures and a choice of narrator voices. Speak your first action, and let the dice fall where they may.

Related reading

This is part of our series on the dangerous half of solo D&D — fights, hazards, and the rules that decide whether your character walks back out of the dungeon:

• Traps and puzzles in solo play
• Skill checks that decide a fight
• Fighting alongside AI companions
• Running climactic boss fights solo
• Solo D&D combat with an AI DM

Start a free adventure in your browser — speak your actions aloud and the AI narrates what happens next.