The explination for the existence of magic generally held among scholars and wizards is that it is an extra dimensional energy that leaks into this dimension through infinitesimal tears in the fabric of reality. Like a particle of radiation, this energy can infiltrate and manipulate matter, warping molecules, genes and altering their nature in bizarre and infinite ways. 

Certain individuals, through uncertain means possess a sensitivity to this magic particle, and rarer still, some are known to be able to manipulate this alien energy through sheer force of will.  

When a wizard casts a spell, they are drawing upon the ambient magical energy of the surrounding region and manipulating it through force of will, to produce the desired effect. How exactly this is accomplished is unclear, through it does seem similar to some psionisist's ability to manipulate electricity or other forms of energy. However, the ability to cast magic seems to require much more mental concentration, perhaps due to the alien nature of the energy. 

In order to help them focus their efforts, most magicians and wizards use set words or phrases to guide their will while casting a spell, in much the same way some students will use rhymes or anagrams to help them memorize facts and concepts. Still others magic users will  use an item to focus both the magical energies and their will, though the danger in this lies  in the possibility of losing the item. 

This elaborate ritual is required because at some point during the spell, the magic gathered from the surrounding region is  completely contained within the body of the caster before being projected in the form of a spell. If a caster where to loose their concentration, the magic would spill out in a random manner, usually resulting in a simple miscast spell, but sometimes resulting in  damage to the caster.   

Casting is a mentally and physically taxing process, represented by the loss of the caster's Energy Points. 
                                                            
 

In game terms, any mage attempting a new spell for the first time will fumble on a roll of 12 or 11. If the GM feels that they are not concentrating sufficiently, then the caster will fumble on a roll of six or more. 

Through a process that can require months of careful study and experimentation, or occasionally through shear luck,  a spell caster can attempt to create a new spell. 

The first method is deliberate and requires that the mage planning out the effects and workings of the spell weeks before they even attempt to manipulate any magical energy. In game terms the player must write up the spell and submit it to the GM who is free to edit or refuse. Once the mage feels they have planned it out, they will then attempt to cast their new spell. The process can take hours as the mage slowly summons and releases the magical energy, examining each sensation and effect. During this procedure the player makes a magic roll as normal and on a result of:
10-12: The spell is a critical failure. Roll on the Critical Spell Failure Chart below.
8-9: The spell fails. The mage must retry again in a week
5-7: The spell partially works. Reroll again in a week with a +1 to the roll
2-4: The spell succeeds. 

The second method of creating a spell is much more hazardous. In times of desperation, the spell caster may be faced with a situation in which they wish to use magic but do not have a spell that will do exactly what they need. 

In this case, the mage attempts to control the magic as it flows through them shaping it through shear force of will. The automatic penalties for attempting such a feat are +1(plus the level of the spell being attempted) to cast, and the roll is a Critical Failure roll with a result of 9 or more. The GM makes up the effects and Energy Point Cost of the spell (about 5 to 10 times the normal cost for a similar spell) and further penalties depending on the situation (taking into account dramatic circumstance). The Player can boost his chances by spending Energy Points, for every additional 5 Energy Points they spend, they gain a -1 to their Magic roll. 
 

If the mage would like to learn a new specialization, then they would have to purchase the Magic attribute again, either taking the general Magic Attribute at 4 points per level, or selecting another field to specialize in for again at 3 points per level. There is no limit to the amount of Magical fields the Mage can take. If at any point the mage takes the general Magic attribute, the bonuses they obtained for having specialized fields still remain. 

Casting any spell at another player or person requires a Combat roll. The caster's Combat Value in such an instance is equal to their initial Combat Value plus their Level of Magic Attribute. If the caster is defending against an attack using magical means (i.e., using a Flame-Bolt to counter an arrow) then they are to use their Defense Combat Value plus their Level of Magic Attribute. Note that in either instance, the initial Combat Value does NOT include bonuses from the "Combat Mastery, Focused Combat or Special Attack/Defense Attributes". It is recommended that players make a note of the character's Magical Combat Value in a separate section.

At Tears and Pools, all mages gain a bonus to their magic roles (-2 to 4 depending on the power of the area) and for every spell cast they must make a roll.
1 The spell is cast normally at half the Energy cost
2 The spell is cost normally but does 2D6 damage to caster
3 The spell is cast but is sent flying in a random target. 
4 The spell gains an added effect. GM's discretion
5 The spell is twice as powerful as normal. Double all effects. 
6 The spell fails. Role on the Magic Critical Failure Chart. 

For every Magic Item brought into such a region roll:
1-2  The weapon takes on another power or spell.
3-4 Any enchantments are doubled in power
5-6 The item begins to act as a magical lightning rod, grounding any nearby magic and doing 1d6 damage ever round the character keeps the item on their person. 
 
At Null Regions the effects can range from double the Energy Point cost to cast, to no spells permitted at all. Both regions have similar effects on Psionics powers. 
In both cases GM's should keep in mind any Special Attacks and/or bonuses that the character's may have and deal with them accordingly.