- The most fundamental difference between d20 and ArM is the d10 vs. d20 roll. Many of the conversions I've made simply adjust for the statistical differences derived from those dice differences. For instance, most dice modifier bonuses from ArM are doubled to get their d20 equivalents.
- Arts are treated as skills. This is at variance from ArM where Arts can only be increased through study and training. However, Art levels will be comparatively low in d20 (particularly initially), and so allowing players to spend experience on them should balance things. Is treating Arts like a skill fair? Normally, it is raised through formal study or training, not “story experience.” The exception is magical affinity, which creates a “skill” that adds to the Art’s total. You could declare that experience cannot raise Arts, or only at an increased cost.
- Why not separate classes for each House? I am mostly concerned with converting the magic system over, not replicating the nuances of the social/political organization.
- A first level D&D mage will be vastly underpowered compared to a beginner ArM guy. A beginning ArM magus is about equivalent with a 8th level d20 mage. A 20th level D&D mage is still not as powerful as an ArM “arch mage.” They would need to be roughly 25th level to be equivalent.
- D&D spell level roughly equates to the converted ArM spell level / 10 (also called a spell's "magnitude").
- Mage casting chances have been set so that a d20 mage will have about a 50% chance of casting a formulaic spell roughly equivalent to the highest level D&D spell they could cast (at their class level) with no fatigue loss. This means even if they miss their roll, they will still make successfully cast, but take fatigue. This means they can also attempt to cast spells one level above them and succeed 100% of the time, but will take fatigue. This means they can cast spells at two levels above, and succeed 50% of the time, but always take fatigue.
- I have deliberately avoided converting the ArM Flaws. Currently, d20 does not support such a concept. I welcome any ideas on how to use the flaws concept in d20.
- I make the general assumption that 1 ArM experience point is roughly equal to 500 d20 experience points.
- Skill difficulty conversion were performed by comparing various task DC examples from the Dungeons and Dragons books, and comparing them to the difficulty rankings in ArM. Also used the table in the d20 Star Wars book (Table 4-4, p. 67) that gives generic difficulty levels.
- I use the assumption that one Body level in ArM is roughly equal to 3d6 damage in d20.
- Method for fatigue uses 1d6 per magnitude. Helps assure balance as HPs increase with level in D&D, but fatigue levels do not typically increase in ArM.
- This means that an 8th level mage (again, what we consider roughly equivalent to a starting ArM magus), will have spent about 320 spell levels to learn spells. This is very close to the 300 spell levels a new ArM character spends on starting spells. Thanks to Damon Butler for this mechanic.
- I base my conversion on comparing the weapon damage ratings from the two settings, and extrapolating to the typically higher damages done by spells. I simplified the conversion to a formula, rather than a table for simplicity. Thanks to Damon Butler for this recommendation.
- Most +1 Virtues were converted to feats directly. For +2 and higher virtues, I added some prerequisite to the feat (in some cases another feat, in other cases a ability score minimum).
