My focus in developing this system is to present, as much as practical, a "simulation" of a low-fantasy world based in medieval Europe. The intent is that this world wouldn?t seem all that unfamiliar to a person living in Europe between 600 and 1600 AD. This drives several concepts in the rules:

Physical Laws:

The physical world of Yellow Tome is your physical world. Concepts of mass and energy and their relationships are conserved wherever possible. A dagger to the heart will usually kill a man no matter what “level” of experience. Men (and elves, hobbits, dwarves, etcetera) cannot sustain the general physical damage of larger beasts so Body (hit point) values for men will not routinely exceed those of a heavy war horse.


The medieval world is steeped in a specific ethical reality where good and evil are distinct elements of everyday life. Generally, this means that the impression of good is supported by religious and political mechanisms and evil is opposed by society at large. The religious classes are therefore modeled upon the Roman Catholic faith prevalent throughout northern Europe in the modeled period. Miracles are thus an act of God/Jahweh/Allah and not the will of the cleric.


I have generally chosen the magic systems to represent neutral mystic technologies. Here I have chosen to diverge from the historical to create the fantasy realm. Societies of the period did not look upon magic as neutral at all. Sorcery was to the mind of the medieval, simply evil. Small enclaves of like-minded scholar/elites might gather occasionally to share discoveries under the protection of a university, but there?s not a lot of Gandalf the Grey in that story line.

Laws of Magic:

It is my goal that magic follow, at least nominally, the laws of physics. A 4 ounce mouse, transformed into an elephant, may still only mass 4 ounces. Physical magics (created elements) are wrested from alternate planes so mass is conserved as they are ?merely? translated at expenditure of significant personal energy.

Play of Magic:

The spell lists are intentionally very limited, but very flexible. As much as practical I?ve endeavored to create malleable magic spells that can be combined and manipulated to create whatever affect the player is looking for. Thaumaturgy and Physical Magics are the best examples of this, where we take from one to six building block spells and combine them to generate the requisite effect. Traumatic and Healing magics target specific biological functions. The way I GM it is casting player to tell the story of his intended action and the Game Master to manipulate the ?formulas? to determine the success, effectiveness and cost of the resulting casting.


The character’s ability to perform an action is based on an equation considering difficulty of the task versus the characters talent, experience and training. I have chosen a multiple eight sided die algorithm that generates success probability along a normal curve similar to that accepted in the social sciences as indicative of population ability. One interesting result is that advancement doesn’t follow a linear path. Nor does advancement follow the popular exponential curve common in MMORG and other modern RPG settings. The effect is that the easy stuff gets easy quickly and then doesn’t change much, while the more difficult tasks become easier at rates tied to the difficulty. The most difficult tasks stay that way until a significant amount of experience is put into general ability training.

Character Maximization:

One (intended) result of the complexity of the skill algorithm is that it becomes quite difficult to design a character expressly to be “the best” at any one thing. Nor is there any one “right” way to build any character type. I won’t lie to you, there do seem to be some nodes where a characters investment of his experience into Base Proficiencies seems to suddenly make a visible difference in his effectiveness. One such node is found at the value “17” in Combat Proficiency, primarily as the rate of attack (blows) for most weapon skills increases at this value resulting in up to a 33% increase in average damage per turn.

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updated on:  29 Mar 2014