There are various different types of magic and they operate in different ways. Some take a greater toll on the user than others but all exact a price for using it.
Blood Magic- Blood Magic is in the realm of life and death and is one of the post powerful, and most feared of the magic types. It is typically used by Necromancers and Blood Elves and is universally feared and hated. Blood magic allows for the control of or linking to blood. Controlling blood like a Blood Elf does, or linking like making a shield or ward that can only be passed by a person with the correct blood. It can also be used to link others to a certain blood line, magically forcing an entire people to serve a single family by linking them all through blood.
Elemental Magic- Elemental magic is exactly as it sounds, it relies on the various elements of Earth, Air, Fire, Water, Lightning, Wood and Metal. Elemental Magic can be utilized by Wizards, Sorcerers, Elementals (only one of each type alive at any one time) and Wild Elves. This is the ability to summon and manipulate the element in question. Varying levels of strength result in varying different reactions or levels of reaction. A weak elment user calling up wind might get a light breeze. A strong user might get a hurricane without meaning to. THe use of elemental magic comes at the cost of energy. This magical energy is different in all people both in level of strength and quantity. The amount of available energy can be built on, just like exercising a muscle. Rest replenishes this energ after expending it.
Mages- A Mage uses an inner core of magic to access energy outside the body. Mages create their magic through spells, incantations, potions, rituals and other forms of magic. Their power doesn't come from within entirely as most of the energy required to perform whatever spell is drawn from the world around them. The slightest misstep in casting one of these spells however can have disastrous results.
Sorcerer- A sorcerers magic is very similar to an Elemental. They use their own inner force to manipulate the external world around them. There are no incantations, potions or ritutuals. The Sorcerer simply applys his/her Will toward what they want done and their magic and imagination takes care of the rest. The slightest thing however can cause extreme exhaustion which again may be built up over time. Attempting to do something the Sorcerer doesn't have the required energy for will
result in death.