Magicka is within every spirit and is the energy within all living things. Magnus, an et'Ada known as the god of magic, was said to be the architect of the mortal plane. As this plane, known as Mundus, was formed, he realized that the et'Ada were sacrificing much of their power in its creation. Many of the lesser et'Ada were vanishing, as their entire aspects were being absorbed into Mundus. Magnus immediately ordered the project be terminated, and left to Aetherius at a great cost. In doing so, he tore a hole in the veil of Oblivion through which the magicka of Aetherius flows into world. The great rift left behind, the sun, is itself known as Magnus.
Soon after, other et'Ada, who would become known as the Magna Ge, fled with Magnus, leaving behind similar holes which became the stars. This is why the star under which a person is born has such great influence on that persons fortunes and fate.
CASTING A SPELL
Refer to the Player's Handbook, chapter 10 for more information regarding spells, cantrips, and rituals. This section will only cover the parts of spellcasting that have been revised or follows different rule sets.
VARIANT: SPELL POINTS
Instead of gaining spell slots to cast your spells, you gain spell points referred to as magicka. Each spell has a point cost based on its level. The Magicka Cost table summarizes the cost in spell points from 1st to 9th level. Cantrips don't require spell slots and therefore don't require spell points.
You expend a number of spell points to cast a spell of a given level. You can't reduce your spell point total to less than 0, and you regain magicka points when you rest, as described in the class description.
Spells of 6th level and higher are particularly taxing to cast. You use magicka to cast one spell of 6th level or higher, but you can't cast a spell of the same level again until you finish a long rest.
The number of spell points you have to spend is based on your class level as a spellcaster, as shown in the Magicka Points column of your class table. Your class level also determines the maximum-level spell you can cast. Even though you might have enough points to cast a spell above this maximum, you can't do so.
Although this system can be applied to monsters that cast spells using magicka, it isn't recommended that you do so. Tracking spell point expenditures for a monster can be a hassle.
To harness the power of magicka, one must have at least one hand free, and be able to speak or, at least, be able to create a resonating sound. Therefore, all spells require Verbal (V) and Somatic (S) components, as described on page 203 of the Player's Handbook.
In rare circumstances, a magic user will require Material components (M), but this is usually reserved for exceptionally powerful spells, such as a resurrection spell. It is possible that unique and powerful rituals that mark pivotal moments of a campaign will require special materials. These events could include summoning a powerful Daedric Prince, opening a gateway to another realm, or channeling an aedric blessing to eradicate a harmful disease plaguing Tamriel, It is up to the DM's discretion to make these requirements clear.
All mortals of Nirn are born with magicka within themselves. Magicka comprises every spirit, it is the energy of all living things and can be harnessed by anyone who devotes themselves to learning its secrets.
This innate ability allows all men and mer to cast spells without the need of a spellcasting focus, as they themselves are the spellcasting focus.
THE SCHOOLS OF MAGIC
All spells are categorized into one of six schools of magic.
Alteration spells distort the local reality through direct imposition of the mage's will. This School concerns itself with magicka's ability to change, often radically, the structure and composition of any object. Unlike the School of illusion, alteration deals with actual change, not the appearance of it. This includes spells of paralysis, water breathing, water walking, lock opening, and personal elemental shields such as flame cloaks.
Conjuration spells summon and bind the spirits from Oblivion and Aetherius. Some spells are used to trap souls, conjure or banish Daedra or other creatures, as well as summon bound weapons and armor. For the sake of classification purposes, the necromantic arts of reanimation, conjuration, and manipulation of the undead.
Destruction spells splinter material bonds by the direct application of force, typically elemental in nature. This includes damaging spells of flame, frost, shock, and disintegration, as well as magic that drains essence or personal attributes.
Illusion spells alter the perception in oneself and in others. They cause people to see things that are not there, to miss things that are there, to hear phantom noises, or to remember things that never happened. Some illusions create phantom images that any creature can see, but the most insidious illusion plant an image directly in the mind of a creature.
Mysticism spells are used to alter the nature of magic itself. These effects are as extravagantly disparate as the creation of magical cells to hold a victim's spirit after death, to the manipulation of objects at a distance. The sorcery behind them is veiled in a mystery that goes back to the oldest civilizations.
Restoration spells resist damage and restores wholeness by reknitting the damage material. The opposite of destruction, this magic is used to heal, create wards, cure disease and poison, and for physical fortification.
VARIANT: REGAINING MAGICKA
If you enjoy games that are fast paced and combat heavy, the characters can regain magicka during short rests, allowing them to cast more spells each day.
You regain magicka limited to your Intelligence modifier while resting. The amount of magicka you regenerate during a short rest is equal to twice your Intelligence modifier. Sorcerer's, due their stunted magicka feature, are unable to regain magicka during a short rest.
VARIANT: LEARNING SPELLS
Instead of learning spells as you level, you can make the world more immersive by requireing to learn spells through study and focus. This creates a lot of downtime activities, which can slow down play, as learning new spells is time consuming. It also makes character's who rely on spells feel weaker early on, as collecting an aresnal of spells will take considerable time.
Magic is learned and mastered through studying and practice. For some races, like the Altmer, magicka flows through their bloodlines and live in a culture that embraces the study of magic. Others, like the Nords, are typically cautious to magic's destructive side. Regardless, they all have magicka within, even if they choose not to learn how to use it.
Classes that use magic, and some races, begin with a set number of known spells. Each time a character reaches a new level in spellcasting, they learn an additional spell, as noted in their class description. Any additional spells must be studied from trainers, usually found colleges and guild halls, or by studying spell books.
Spells can be learned much faster from spell trainers than from studying spell books, but trainers can be costly. A spell learned from a trainer requires 4 hours of study and 50 septims per spell level, beginning with Cantrips. For example, a 1st level spell, requires 8 hours and 100 septims, and a 7th level spell requires 32 hours of training and 400 septims.
You can study from a trainer up to 8 hours a day. To determine how much knowledge has been retained, roll a die equal to the hours studied (1d8) and add the character's Intelligence modifier. Studying from a book requires twice as much time, but spell books can be found while adventuring, but they can sometimes be purchased from guild halls for half the cost of training.
Talented mages are capable of crafting spells, either through trial and error, or with the aid of a master. Spellcrafting Altars can be found in most universities and colleges where the imagination and innate talent is the only restriction.
The creation of a spell has the same cost as training in a spell of equal skill level, usually spent on rare inks and component, but the process takes twice as long since constant practice is required to create something unique. The spellcrafter must know the effects from another spell to create a spell that uses a similar effect. To create a spell, work with your Dungeon Master and use the guidelines presented in the Dungeon Master's Guide.
REDUCING SPELLCRAFTING TIME
Once each day, when a spellcaster spends time researching a spell they are crafting, they are required to make a Spellcrafting Check. This check is treated as though you are casting a spell with your spell attack modifier. The DC of this check is equal to 10 + the level of the spell being created.
On a successful check, the crafter can roll an additional die, equal to the time spent researching, to reduce the total remaining time. No time is reduced on an unsuccessful check, however, a critical failure and a critical success both reduce the time by twice the normal amount. We often learn more from our mistakes than from minor successes, and this is reflected in spell creation.