Magical power in the Marvel Universe is divided into three different types: personal energies, universal energies and dimensional energies. All magic power is built on common ground, that of reshaping existing power, found in either yourself, your universe, or summoned from other dimensions, to form that which you desire.
Mechanics of Magic in the Marvel Universe
The mechanics of how magic does what it does is still not clearly defined (not a surprise). It is implied that there are some sentients who have an affinity to altering, temporarily or permanently, the physical laws of the universe by sheer will power itself.
The magic in the Marvel Universe come from three primary sources:
- the tapping of one's personal spiritual energy or soul force
- tapping the energy hidden in your universe or nearby realms of power
- power borrowed, stolen or loaned from near-divine, divine or infernal beings
Marvel has hinted that the true source of all magic comes from the energy of the sun being filtered or manipulated via mystical forces and this is why the forces of good are often associated with the power of light. It is what gives the Doctor Stranges and Shamans of this world their advantage that ultimately darker forces are forced to yield to the sun.
Personal Energies are those derived from the life force of the Sorcerer. Continual use of such energy would rapidly deplete a normal being, consuming his life energy and thus leaving him dead. Sorcerers learn, through meditation techniques and trained willpower, how to activate these latent human abilities and use them for their own needs without seriously depleting their life forces. Personal Energies can only be used to power abilities developed through mental studies and are thus mainly limited (and represented) as Mental Powers. Examples include (but are not limited to) Hypnotism, Mind Control, Astral Projection, and Telepathy.
Sorcerors can tap into the Universal Energies of their home dimension and draw forth magical energy for their spells. This can be a tiring task and is often done using an object or focus to ease the cost of energy and wear and tear on the sorcerer. Objects such as the Orb of Agamotto, the Cloak of Levitation, orbs, staffs or wands. Universal energies are typically used for teleportation, conjurations, dimensional traveling, illusion-casting, energy projection, energy shields and so forth. Basically, any spell cast that requires no verbal entreaty and is not Personal in nature (examples: Shields of Serephim, Bolts of Bedevilment, etc.)
Invocation - Tapping power from the Gods
Dimensional Energies are those bestowed upon a sorcerer from an other-dimensional Entity. These beings do not usually live in the same dimension as the sorcerer and will offer to trade spells, magic or power in exchange for worship, sacrifice, or an opportunity to later invade their dimension. These Entities must be entreated by the sorcerer using ritual spells and possibly sacrifices or promises. Once entreated, an Entity then bestows the power to work the spell upon the sorcerer and the spell is completed. Spells like these include the Flames of the Faltine, the Crimson Bands of Cytorrak, the Winds of Watoomb or the Roving Rings of Raggador.
These representations are built around the most well known sorcerer of the Marvel Universe, Doctor Stephan Strange. There are many other practitioners of magic who may have different means or subsets of magical ability. Some will limit themselves to particular subsets such as Alchemy, Voodoo, or Witchcraft. This limitation may be based on opportunity or exposure to a particular realm of magical.
As to any particular dimensional realm or entity indicating that THEY are the Source of magic, there is some truth to the statement, but not quite the way they make it sound. They may be A source of magic, but rarely are they THE only source (example: The Dark Dimension, realm of Dormammu). The only time that might be true is if they are inhabiting a realm they created themselves. This might make them quite powerful there since they would be limiting the ability of other magic to work there.
Reference: The Official Handbook of the Marvel Universe