Rules tweak for Ars exploding rolls

I love the concept of a stress dice in Ars Magica 5th edition, and liked the Quality dice roll in the older editions too. One aspect that slows a table down is when a 1 is rolled on the stress dice and doubling mechanic kicks in.

As a player I dislike the rolling a 1 then a low number as it makes the “doubling” result somewhat disappointing. In stress rolls it is also a little odd in the number distribution of a 1d10 roll to have a zero as a potential botch and a one as the potential for greatness.

So instead I’m pondering a 1d10 roll where a result of 1 is a check for botch, and a 10 causes an additional roll where 10 is added to the result. Then the botch check treats a 1 as bad instead of a 10 so that the rolls are consistent. A further tweak might be skip the additional roll equal to dice+9 rather than +10, to distribute the result. Each 10 rolled in a row indicates a +9 on the next roll.

What will it be like in play?

Very similar to current, and more logical.

Rolling your Vis stores

A typical wizard or covenant should have a store of Vis. This might be a few pawns, or may be substantial depending on the character age or covenant season. Allowing PCs to assign their vis is a good thing, but if it cannot be agreed, or if a random solution is desirable, try this.

While pondering the problem looked for (a) way to roll random numbers, (b) way to associate them to each art, (c) allowance for special types of Vis, and (d) allowance to alter how common each type is in the setting by applying a weighting or scarcity value.

As a starting place this could be a scratch pad with 1-20 written down, arts assigned a number, and a d20 in your hand. Pretty simple for one off needs. I decided to use a spreadsheet to do it, because it is a small task I’ve had to do many times and it keeps being a pain. This gave the flexibility to muck about with the weighting and determine a large amount of vis in one go.

Perhaps one of the days I’ll make one for spells and books too.


  1. Setup the spreadsheet to show each type of vis you want. By default the 15 types are present in mine, and there are 5 additional slots for other types should they be desired. My suss is realm aligned types, saga specific types, or perhaps hybrid types are there, they should be rare compared to the norm.
  2. Update the scarcity of each type. Some sagas make particular types rare and other common. e.g. If the magus goes gathering amongst the mountains an Aquam find should be unlikely, and Terram more common.
  3. Confirm the amount you want, but adding or deleting rows in the Random area. The sheet generates up to 40 without too much hassle; and adding more is easy as sliding the rows down.
  4. Copy & paste the result text into your summary, covenant, sheet.


Its as rough a spreadsheet as you’d expect, but it works. It’s also easy to tweak for generating huge volumes of vis, say a covenant wants hundreds of pawns, and it makes sense for that covenant to have a broad selection of vis.

I know of a quirk in the RNG and math applied to determine the Art, but it is small enough to be inconsequential.


Alternate Rolls for Ars Magica

A surprisingly good idea came from the Atlas official forums by user: Humboldtscott for Ars Magica stress dice rolls, which is worth promoting. As said in the forum there are some quirks in ArM for dice rolls which might be confusing to new players. Continue reading