CIRCLES OF MAGIC
Although most mages are taught the 9 power levels of magic and priests the 7 power levels of faith, few are taught the circles of magic until much later in their lives, if they ever attain the level of mastery(10th level, but some learn at 9th). They are then taught something that almost always shocks them, especially because it is so fundamental to their art. The reasons for why such teaching is postponed until this time are many, but the fact remains that only a few learn of this knowledge before this time.
There are 3 circles of magic that exist for mortal men. Although 7 circles actually comprise magic as a whole, the upper 4 are reserved for the gods alone. These circles represent the capacity of magic, that is, how much potential it has. Originally, when these circles were the only classification for magic power, it was observed that the spells of a given circle varied greatly in power. Thus, subdivisions were made to better classify spells into tighter levels. These became the spell levels as we now know them. At that time, 1st-3rd level spells fell into the 1st circle of magic. 4th-6th level spells fell into the 2nd circle of magic. 7th and higher level spells fell into the 3rd circle of magic, this includes true dweomers, which represent the pinnacle of mortal accomplishment, and although very powerful in effect, they are still mortal dweomers. Quest spells are actually a part of the 4th circle, being actual divine manifestations of power, not like the mortal magic of the first 3 circles. Demigod power fell into the 4th circle. Lesser god power fell into the 5th circle. Intermediate god power fell into the 6th circle. Greater god power fell into the 7th and final circle. It is theorized that there may be an 8th or master circle of magic, and if true, this would be the circle all Highgods, such as Ao, fall into(in fact the theory predicts 12 circles of magic, and it is this theory that lends credence to the idea of power hierarchies among the Highgods.)
A good analogy to compare circles and levels is a bucket and various liquids. The bucket is a fixed volume, so it can only hold so much liquid. However, the various liquids may be more or less valuable than other types, thus, filling up the bucket with water would be less valuable than filling it with fine wine. The value of the liquid would be like the levels of spells and the bucket size would be like the circle the spells are held in. Thus, there is a limit to how much power a spell will give, determined by the circle. Although both 1st and 3rd level spells may be held in the 1st circle of magic, 3rd level spells are more powerful than 1st. This is related to the liquids of different values. 3rd level spells are like fine wine while 1st level spells are like water. However, because the bucket is of limited size, only so much of the liquid, or power can be released. Circles limit the maximum power that a spell can be cast at.
1st circle spells are limited to 10th level as the maximum casting level that can be used by the spell. This includes only true spell effects that depend on the casters level. Range and Duration are not true effects of the spell, but parameters that allow the caster to place the spell where he needs it and determine how long its effects will persist. These 2 parameters are not limited by the circle, because they are not in a circle, not being a part of the spell, rather, they are external to the spell, and are directly influenced by the casters level of mastery(casting level), how well he can control and manipulate the placement and duration of the spells effects. Although the spell's power and effect will influence how well a caster can manipulate and control it(range and duration vary from spell to spell), this is an indirect influence, and does not make these 2 external parameters a part of the spell, just influenced by it. Hence, only the power or effect of the spell is limited by the circle, because these are a part of the true spell and are, therefore, in the circle. Although a higher level caster may use the spell, he only gets out of it power equal to the maximum the circle will support. 2nd circle spells are limited to 20th casting level and 3rd circle spells are limited to 30th casting level(the maximum level achievable by mortal man). Thus, a fireball is limited as a 1st circle spell, to 10th casting level. Lower level casters can only fill the bucket to a certain level before running out of power, thus they can improve as they advance in power. But a point is reached where they fill the bucket full, then, even if they could add more, the bucket would not hold anymore, so they reach the limit. They become masters of that circle. Thus, 10th level casters are masters of the 1st circle, 20th level are masters of the 2nd circle and 30th level casters would be masters of the 3rd circle.
Although spells usually fall into the level range given above as to which circle they belong to, this does not always need to be the case. A 3rd level spell could be researched in the 2nd or even 3rd circle, for example. This would cause it to be weaker on a per level basis than other spells of its level, because it has been elevated to a higher circle, making it harder to cast. Thus, to keep it at the same power level, 3rd, it must be weakened a bit. But, when used at its full potential, it will be more powerful than other spells of its power level. For example, a new spell, fireball II is created. It will mirror fireball, except be of the 2nd circle. This will cause it to be weaker on a per level basis than fireball. It would cause d3 damage per level with the same area of effect. Since fireball does d6 damage per level, we see that fireball is better at lower levels. At 10th level, fireball reaches its max. It does 10d6 damage. Our new spell at 10th level only does 10d3 damage. But at 20th level, when our new spell reaches its max., fireball still does 10d6 damage(35 average, 60 max.), but the new spell does 20d3 damage(40 average, 60 max.). Thus we see that the higher circle spells only benefit those who are able to get the full punch they offer, by being high level. A 3rd circle version of fireball, fireball III, would do d2 per level, for 30d2 damage(45 average, 60 max.) at 30th level. Thus, we see that the total(max.) power available does not change(all the spells are still 3rd level after all), but the efficiency(average power per casting) does get better, as we would expect from a higher circle spell.
Masters of the Circles
At the first, mages and priests had titles based on circles of magic. A 1st level mage would be a 1st order mage of the 1st circle. A 12th level mage would be a 2nd order mage of the 2nd circle. A 10th level mage would be a master of the 1st circle. A 10th level priest would be a lord of the 1st circle. A 2nd level priest would be a 2nd order priest of the 1st circle. The magi and priests adopted individual titles peculiar to their land, thus, the true titles were lost over the years.
Although a master of a circle can no longer cast spells of that circle at any greater power, because he has mastered the circle, he does gain benefit when using such spells. Every 3 levels a master is over the level of mastery for a circle, he imposes a -1 on the saves of targets of those spells. This level of the master only includes his specialist bonus for being specialized in a spell or a specialist of the school that spell is in. This +2 to casting level is added on and counted toward finding the masters true level. Spell boosting to increase casting level does not count when calculating this level. This shows how a master can attain such control over a mastered spell, that although unable to get anymore power from it, he can shape it and send it at its target in such a manner that the spell strikes at the targets weak points, inflicting a penalty to the targets chance to avoid its effect.
Other benefits gained can include being able to move while still casting the spell at a rate up to the number of levels the master is over the minimum to master the circle the spell is in. Thus, a 14th level mage could cast a 1st circle spell while moving up to MV 4, since he is 4 levels over the mastery level for 1st circle magic. The mage can cast such spells in armor, being required to make a DEX and INT check at a penalty equal to the spell level but with the number of levels over the mastery level as a bonus. Thus, the 14th level mage using a 3rd level 1st circle spell must check both DEX and INT at -3 for spell level and +4 for being 4 levels above mastery level for the spell, thus his final modifier is +1. Such mages can suffer damage and still retain concentration to finish the spell. If damaged, the mage must save vs. death to successfully cast the spell. This save is modified by -1 per point of damage suffered and +1 per level over the mastery level he is. So the 14th level mage is casting a fireball. He is hit for 6 points of damage from 1 attack, and 12 points from another. He must pass 2 saves to cast the spell. The first save is modified by -6 for the damage and +4 for the level above mastery level, thus his final modifier is -2. The other save is at -12 and +4 for a final modifier of -8. If he passes both saves, the spell goes off. The DM can allow other bonuses, but keep them in line with these. Some masters may need to learn proficiencies to get these other benefits.