Dune: Adventures in the Imperium, by Modiphius, runs on the studio’s 2d20 engine — the same family that powers their Star Trek and Conan games, tuned here for schemes, houses and the razor politics of the Imperium. It rewards teamwork and daring, and it makes even a failed roll interesting.
The dice and the core mechanic
The system’s name says it: you roll two twenty-sided dice as your base pool. A handful of d6 — the “combat and effect” dice — appear for damage and special results, but every test starts with a pair of d20.
Your target number is built from your character: an attribute (called a drive or skill depending on the edition’s framing) plus a relevant skill or focus, added together into a single target number. Crucially, this is a roll-under system — each d20 that comes up at or under your target number scores a success.
How a roll resolves
The GM sets a Difficulty, usually 0 to 5, which is the number of successes you need. You roll your 2d20; each die at or under your target number is one success. Total your successes and compare to the Difficulty — meet or exceed it and you succeed.
| Each d20 result | Successes it scores |
|---|---|
| At or under your target number | 1 success. |
| At or under a low “critical” threshold (often 1, or a focused value) | 2 successes — a critical. |
| 20 (or a high value) | 0 successes, and typically a Complication. |
Extra dice. Two d20 is only the start. Before rolling you can buy bonus d20 (up to a cap, usually three extra for five total) by spending Momentum from the group pool, adding Threat to the GM’s pool, or accepting a point of harm or other cost. More dice means more chances at successes — at a price.
Momentum and Threat. Beat the Difficulty and any leftover successes become Momentum, a shared group resource you can save and spend to buy dice, gain information, or improve later rolls. The GM has a mirror-image pool called Threat, which they bank when you take risks and spend to complicate your life. This two-sided economy is the beating heart of the game.
Complications. A high die (commonly a natural 20) doesn’t just fail — it introduces a Complication, a narrative snag the GM can trigger now or later. You can often still succeed while picking up a Complication, so a roll can go well and badly at once.
Effective strategy
Spend Momentum, don’t hoard it. The group pool decays between scenes, so unspent Momentum tends to evaporate. Convert good rolls into extra dice, information, or setup for the next crucial test rather than sitting on a stockpile that fades.
Weigh the cost of extra dice. Buying dice with Threat literally arms the GM against you. Reach for bonus dice when a roll really matters and you have a comfortable target number; on a marginal target, extra dice also multiply your chance of Complications.
Raise your target number first. Assistance from allies, the right asset, and appropriate focuses widen the “success band” on each die. In a roll-under game, a higher target number is worth more than an extra die, because it improves every die you roll.
Think in the fiction of intrigue. Dune is about houses, agents and leverage as much as combat. Use assets, contacts and clever framing to lower Difficulty or gain bonus dice through the story, not just the maths.
Because the base roll is two d20 you read against one target number, you can roll 2d20 in your browser and count how many land at or under your number.
Beginner tips & common mistakes
- It is roll-under. Each die wants to be at or under your attribute-plus-skill target — low is good.
- Successes, not totals. You count how many dice succeed and compare to the Difficulty; you never add the two d20 together.
- Extra dice have a price. Momentum, Threat or harm buys them — and Threat comes straight back at you.
- Momentum is shared and fleeting. Pool it with the group and spend it before it decays between scenes.
- A 20 usually means a Complication. Even on a success, a high die hands the GM a narrative hook — expect it.
No dice at the table? Dice Drop rolls real physics dice in your browser — pools, exploding dice and modifiers built in.
🎲 Roll dice freeWant another success-counting dice-pool game? Read our Forbidden Lands dice & strategy guide.