Magic in the Marvel Universe is known to come in four basic methods, known as egocentric, ecocentric, exocentric, and necromantic.
Egocentric magic is the magic of the self, drawing upon personal energies. This magic operates primarily for the powers of the mind and soul: astral projection, telepathy, hypnosis, and mental illusions are a sampling of egocentric powers. Some mages who are of an extradimensional hybrid nature – such as Clea – and most demons are able to provide their own personal energies for magics more commonly performed using the other methods by mortal sorcerers.
Ecocentric magic is the magic of the universe, drawing upon ambient energies to perform more blatant feats of magic, including but not limited to manipulation of the four classical elements, forming eldritch bolts and shields, and similar effects. Most mystic talismans and relics that exist operate on universal energies.
Exocentric magic is the magic of the beyond, entreating extradimensional entities – often called principalities – for energy. Most principalities called upon have what are called "signature spells", unique spells which the principality empowers directly. Some principalities are entire extradimensional races (such as the Faltine and the Seraphim), but most are individuals on the same power as and straddle the line between gods and demons.
Necromantic magic, also known as "black magic", is the magic of death. This method of magic draws energy from the unwilling, often (but not always) by killing living beings to use their energies. This method of casting magic tends to have a corrupting influence on its practitioners, with those who rely primarily on black magic slowly losing their humanity unless steps are taken to purge themselves of this corruption on a regular basis.
Sorcerers, such as Doctor Strange and his order, deal with six main Realms: Mind, Space, Time, Spirit, Energy, and Matter. These six Realms make up the cornerstones of the Multiverse, and dedicated practitioners can learn up to five tiers in those Realms. Lesser mystics often focus on narrower sub-realms. For instance, Romani magic, as practiced by Wanda Maximoff, relies on the Illusion, Luck, and Matter Realms. Nature-oriented mages often use the Nature Realm, or learn distinct Animal, Earth, Fire, Plant, and Weather Realms. Most of these practitioners only achieve the third tier, with a select few achieving the fourth or fifth. In all cases, a magician's maximum potential level in any Realm is dictated by his Magery level. Magery 0 tends to be innate, but all levels of Magery including Magery 0 are learnable advantages in the Marvel Universe.
The level of the Sub-Realms stack with those of the primary Realm, although the sorcerer does not need to have the primary Realm in order to have a Sub-Realm (in fact, it's usually pretty rare for a sorcerer to have both). For instance, a sorcerer could have Energy/3 and Fire/2, where Fire is a Sub-Realm of Energy; the sorcerer would have an effective Fire/5 because Fire is included in Energy. Note that the cap of Magery is still in force; with Magery 3, a sorcerer cannot have both Energy/2 and Fire/3 and expect them to stack at Fire/5, since Fire/5 exceeds his Magery.
In all cases, the sixth tier of a Realm is off-limits to all corporeal beings. Even such beings as the Olympian, Asgardian, and Heliopolitan gods are unable to achieve the sixth tier in any Realm and remain corporeal. In essence, any being who achieves the sixth tier in a Realm automatically becomes the living embodiment of that Realm, and becomes a truly Cosmic being.
Realm/1 spells use 0 energy, Realm/2 spells 1 energy, Realm/3 spells 2 energy, Realm/4 spells 5 energy, and Realm/5 spells 10 energy. It is possible to mix energy sources in a spell, and most sorcerers will always attempt to use the method that causes them to use the least amount of personal energy.
Egocentric magic focuses on the Mind and Spirit Realms and their sub-Realms, and is powered by the mage's own Fatigue Points (FP) and/or Energy Reserve (ER). (Quintessence Points/QP are used when utilizing The Fifth Attribute in Pyramid #3/120: Alternate GURPS V.) Mages who utilize their own energy for Realms other than those two are required to have the Extra Options Perk for each additional Realm.
Ecocentric magic utilizes the rules on Threshold Magic from pages 76 to 82 of GURPS Thaumatology, with the following setting switches and adjustments: The caster's Threshold starts at 30. Instead of the usual energy discount thresholds described in the Basic Set and GURPS Magic (one less energy at skill 15, another one less at skill 20, etc.), the caster can take a cumulative penalty to reduce the strain the spell puts on the environment, effectively reducing the tally cost by 1 per each -5 penalty to skill. Places of power (the Great Pyramids of Giza, Dr. Strange's Sanctum Sanctorum at 177A Bleeker Street in Manhattan, etc.) give a discount on the energy tally up to 50%. The Increased Threshold advantage (Thaumatology, p. 78) can be taken at the 1/level rate for a 4% increase per level in the Threshold. Recovery of the sorcerer's tally happens at the same speed as recovering FP or ER. And the Variable Energy Access advantage (Thaumatology, p. 79) is not available. Ecocentric magic deals primarily with the Energy, Matter, Space, and Time Realms, although ecocentric spells utilizing the Mind Realm are possible.
Exocentric magic requires a Reaction roll for each entity called upon in a casting unless the sorcerer has obtained a prior Reaction of Neutral or better from the entity in the past. If for any reason the sorcerer upsets or gains the enmity of the principality in question (such as Dr. Strange opposing Dormammu in the Dark Dimension after calling upon him for energy early in his career) and then attempts to again call upon the entity, all further Reaction rolls at at -10 until the sorcerer makes amends (this could be a roleplaying plot point!). If the Reaction roll for a casting is worse than Neutral, the sorcerer must invoke another friendlier entity or obtain the energy from some other source. The sorcerer must have Spirit/3 in order to call upon a principality for energy, but the spell costs a total of 1 energy to cast should the principalities invoked agree to provide energy.
Necromantic magic, like egocentric magic, uses Fatigue or an Energy Reserve (or Quintessence Points if using The Fifth Attribute). However, this energy comes from other living beings, usually unwillingly. Necromancers may prefer to kill their energy sources because the energy released at the time of death is the sum of the victim's Fatigue and Hit Points. At the end of the day when the sorcerer derives energy in this manner, he must make a Will+Magery roll at a penalty equal to the 1/10th the energy derived from unwilling victims. On a success, nothing happens; on a failure, the sorcerer gains a level of Black Magic Taint for every 10 points (or fraction thereof) by which he failed. The Black Magic Taint acts as a penalty to all Realm skills except when using necromantic energy, counts as a -3 point/level disadvantage, and otherwise follows the rules for Black Magic on page 156 of GURPS Magic.
Of note, there are various psychics – such as the Indian psychic Topaz – who can act as familiars to sorcerers, using their psychic talents to amplify or focus the spells of the sorcerer.
In addition, there are a number of additional options which differ from the standard Realm Magic described in Thaumatology.
First, the maximum damage done is at the Realm level squared per round of build-up. Afflictions are resisted at HT or Will at a penalty equal to the Realm level squared minus one. For example, Realm/3 permits a 9d Energy or Matter attack, or a resisted Mind affliction at Will-8 (equal to 9 levels of the Affliction advantage with Malediction).
Range penalties are assessed using the Size and Speed/Range Table (Basic Set, p. 550) for most spells; information spells and most Mind, Spirit, or Time spells use the Long-Distance Modifiers table (Basic Set, p. 241), with Time treating "miles" as "days".
A spell does not need to use the sorcerer's full Realm level. For example, if a sorcerer has Time/5, he may choose to cast a Time/2 spell, at Time/2's energy cost.
Spells that use multiple Realms use the energy cost of the highest Realm used, plus 1 energy for each additional Realm in the spell.
Spells are single-target spells by default. It costs 1 additional energy to turn a spell into an area effect spell with a radius of 2 yards, and then 1 additional energy for each doubling of the radius.
Direct damage spells and weapons (mundane or conjured) can have an Armor Divisor added to them. It costs 1 energy to add an AD (2) to a spell or weapon, and then 1 additional energy for each additional level of Armor Divisor. Remember that the additional levels are (3), (5), (10), (100), and (8); it costs 6 energy to make an attack that bypasses DR completely. If removing an armor divisor from energy weapons, each additional step again costs 1 additional energy per level; the progression here is (8), (100), (10), (5), (3), (2), (1), (0.5), (0.2), and (0.1), starting with the weapon's initial armor divisor.
While many spells are instantaneous, some spells have ongoing effects instead; for instance, a hypnosis spell or a conjured waterfall. An ongoing spell lasts for one minute by default. For double the energy cost, the spell may last for an hour; for triple the energy cost, the spell may last a full day; and for ten times the energy cost, a spell can be made permanent.
(These changes are intended to provide more stable castings than Thaumatology provides, where variables such as duration, range, and area of effect are subject to the Realm skill's margin of success.)
Energy: This far-reaching Realm includes all types of energy, including but not limited to cold, electricity, heat/fire, kinetic, light, radiation, and vibration.
Matter: This Realm deals with altering and creating matter in all forms. A sorcerer's own scientific knowledge does affect the Realm's use.
Mind: This far-reaching Realm deals with all aspects of intelligence and conscious thought, as well as subconscious desires.
Space: This Realm affects such things as movement and inertia, permitting such wide effects as levitation, telekinesis, teleportation, flight, and even dimensional travel. Combined with Mind, it permits clairsentience.
Spirit: This Realm deals with all aspects related to a being's soul or spirit. It can also be used to deal with spiritual entities of all levels.
Time: This Realm affects both the passage of time, including the ability to travel backwards in time, as well as precognition and psychometry.
Air: This sub-Realm of Matter enables the mage to manipulate the classical element of air.
Body: This sub-Realm of Matter deals solely with the manipulation of living (and dead) organic matter.
Dreams: This sub-Realm of either Mind or Spirit permits the sorcerer to travel into and affect a dreamer's dreams.
Earth: This sub-Realm of Matter enables the mage to manipulate the classical element of earth.
Fire: This sub-Realm of Energy enables the mage to manipulate the classical element of fire.
Illusion: This sub-Realm of Mind deals primarily with creating and dispelling illusions.
Lightning: This sub-Realm of Energy enables the mage to manipulate electricity in all forms.
Luck: Also called Probability, this Realm deals with manipulating probabilities in order to alter circumstances to make the improbable probable. This Realm is a sub-Realm of both Matter and Time; someone with both of those Realms doesn't need Luck.
Water: This sub-Realm of Matter enables the mage to manipulate the classical element of water.
As advantages, the Realms of Energy, Matter, Mind, Spirit, Space, and Time are all 20 points per level. Body, Fire, Illusion, Luck and all other Sub-Realms are 10 points per level, being essentially the parent Realm with a Specialized (-50%) limitation on it.
Any sufficiently advanced technology is indistinguishable from magic.
– Arthur C. Clarke's Third Law
Any sufficiently analyzed magic is indistinguishable from SCIENCE!
– Phil and Kaja Foglio's Heterodyne Corollary