GURPS magic systems in D&D

Related material: D&D to GURPS (Introduction) and Building D&D Magic Items in GURPS
==Introduction==
GURPS has several magic systems but most (but not all) are variations of the core system in GURPS Magic making it the required book. GURPS Fantasy and GURPS Thaumatology are also strongly recommended for additional rules, concepts, and ideas. If you want to do a complete conversion and actually build individual spells (Magic as Powers) the Basic Set becomes a must have but that is recommended for GMs who are considering taking their campaign over to GURPS or want to "build" complex magic items. 
GURPS Fantasy and GURPS Thaumatology have streamlined the mechanics of magic, making tailoring the core GURPS magic system to your particular campaign far easier than it was in GURPS Classic. As a result Classic books like Classic: Religion and Classic: Spirits are more useful for the ideas regarding Clerics in them than for any mechanics they have.
It should be noted GURPS Magic is more utility than damage focused as demonstrated by Magery 0 Magic in World Building. Sure, barring special conditions like Wild Mana, the raw damage output potential seen with D&D magic isn't there but that is offset by flexibility - your spell casting class isn't left twiddling its thumbs spell casting wise if it has burned through its daily allotment of spells.
===Quick Glossary of GURPS terms===
GURPS Thaumatology codified several terms for GURPS 4e magic:
*Book: A collection of rituals linked conceptually or by tradition and presented in a single source – often (but not always) an actual, physical book.
*Path: Branch of ritual magic focused on a particular type of effect, encompassing a collection of closely related rituals.
*Adept: Anyone with the Path/Book Adept advantage.
*Charm: Item empowered through a spell ritual or Alchemic process. Protective charms are often called amulets, while charms that draw things to the wearer or allow them to invoke an Alchemic Elixir on themselves are called talismans.
*Fetish: Item containing the essence or power of a spirit.
*Focus: Item that aids in the performance of ritual magic.
*Mage: any being who possesses the Magery advantage regardless of their ability to use magic.B234, GURPS Magic pg 5 It can be tweaked via enhancements and limitations with a certain combination of these resulting in Power Investiture.
*Magician: Anyone with the Ritual Magic skill or uses Ritual MagicGURPS Thaumatology 122
*Malefice: a general term for a symbolic or sympathetic representation used to cast hostile magic at a distance.
*Mana: The ambient magical energy manipulated by arcane spells. In some settings (like Roma Arcana) it represents how many "free" spirits that can "run errands' for wizards.
* Ritual Magic: Also the name of a skill this is where magic use depends on a single “core skill,” typically Ritual MagicBasic Set pg 218 or Thaumatology Basic Set pg 225. Each college of magic is an IQ/Very Hard “college skill” or “path” that defaults to the core skill at -6. College skills have the core skill as a prerequisite and may never exceed the core skill.
*Sanctity: The divine equivalent of mana that represents a deity's power in a given locale.
*Wizard: Someone who can cast spells regardless of them having MageryClassic GURPS also used "Wizard" to refer to anyone with a 25+ skill (Basic Set (Third Edition) Revised pg 45)Yes, This means that in GURPS terms classes like Bards, Clerics, Druids, Paladins, Rangers, Sorcerer, and Warlock count as "Wizards"
==Setting the Foundation==
Mana comes in several different levels and can be Aspected (penalize some spells while giving bonuses to other). For simplicity assume normal mana with magery learnedHigh and Very High Mana are problematic because of the number of available spells non-mages can learn and cast 
The Wild Mana type should be limited to the Outer planes where it will be heavily aspected - as long as a spell succeeds it take no energy cost but any failure requires the spell’s full normal energy cost burning through FP and then HP. If this total is equal to or greater than 5xHP + current FP you are dead. If it is equal to or greater than 10xHP + current FP your body, barring advantages like Unkillable 2 or 3, is totally destroyed. If that wasn't enough there is also roll on the Critical Spell Failure Table.
Sanctity varies with the power of a deity and what is Very High Sanctity (a temple) to one deity can be No Sanctity to an another. For example, a temple to Gruumsh (Very High Sanctity to his clerics) would be No Sanctity to a Cleric of Maglubiyet and vice-versa because they are so opposed to each other.
==Beyond Wizards==
Normally when people say magic they think spellcaster but that is not all there is. First there are magic items and no not all of them come from a wizard’s lab in the form of enchanted items. Natural, Alchemic, Fetishes, and Holy Relics are all items that may not have a wizard behind their creation.F22-F28; GURPS Thaumatology 112-113 Even some Enchanted Items may have had no wizard involved in their creation.
Second, in addition to to non-enchantment magical items there is the type of magic available: Low, Formulaic, and HighFantasy p 147-152. D&D worlds tend to focuses on High Magic to the point Low and Formulaic Magic are almost invisible (though they can show up in the creation of magic items). This is where GURPS Fantasy, Magic, and Thaumatology are head and shoulders over anything D&D has to offer as they provide a wealth of information; enough in fact that with a little work you can emulate about any magic system you want (such as the Slayers Anime)
==Becoming a GURPS wizard==
In the spell system there several different mechanics each with its own strengths and weakness F155-168. For the sake of simplicity treat magical advantages (like Blessed, any form of Magery, and Power Investiture) as "always available" Feats while treating everything thing else (including Ritual Magic and Thaumatology) as skills.
Fantasy’s Magical Arts chapterFantasy p 146-172 is invaluable for sorting through the majority of options available. The many types of Magery available may seem a little daunting but they are are some familiar options here; Restructurable Magery can easily produce something similar to the cast and forget (in this case cast and use up Fatigue) system used by D&D. GURPS Thaumatology can be used to further refine this emulation.
Fractional Magery can serve as a mechanic to allow Magery 0 to be learned and there are various machinics for spells that require higher magery to be cast. Similarly powers that can grant Blessed or Power Investiture will not be too picky initially if their ability to function in the world is dependent on worship. 
The advantages of Magery and Blessed/Power Investiture fit very well with the idea that arcane and divine magic are fundamentally different and the variants of Magery will help keep classes like the Sorcerer and Cleric distinct from the other Magery based wizards available.
Since in D&D the amount of the attribute determines the level of spells it is easiest to assume the bonus to reflect the level of Magery or Power Investiture the character can start out with as shown in this chart:
:Modifier 0 = Magery 0; Blessed advantage
:Modifier +1 = Magery/Power Investiture 1
:For each additional +1 = +1 to Magery/Power Investiture
However the bonuses from an advantage are added in last for base skill level. The reason for this is if there are any defaults (such as with Ritual Magic) the advantage is added in after the default values are calculated.
==Spell Skill Level==
Spells in GURPS are either hard or very hard skills (Ritual Magic has the colleges themselves as very hard skills and the spells within each college as hard techniques). In D&D treat these as Class skills starting at IQ-2 for hard and IQ-3 for very hard (techniques go from the default). When figuring out skill levels for Ritual Magic remember that advantages are added after the skill level and any related defaults are calculated.
Because spells in GURPS are (generally) skills GURPS wizards can easily have dozens of spells even at low point totals. The flip side of this is as skills each spell has to be improved individually. For this reason give D&D spellcasters (level+1)*attribute points in addition to what they normally get to buy spells with. That may sound like a lot but remember spell improvement is not automatic with GURPS spells; those extra skill points are needed to not only improve existing spells but to obtain new ones.
Fatigue is what powers spells and it is figured from HT (CON in D&D). Skill level not only determines the amount of ritual needed for the spell but also when high enough lowers casting time (for most spells) and energy costs. At skill 15 and every 5 levels afterward energy cost is reduced by 1 point. So a spell known at Skill 20 costs 2 energy points less than the same spell known at 14.
Since D&D hit points represent actual physical damage, skill, luck, and battle sense the effects of injury on spell casters as outlined in GURPS Magic needs to be modified. The easiest modification is to divide the total hit point by 10 and round down using the result as the ratio of injury penalties. For example say a D&D wizard has 25 HP. This means that for every 2 points of damage he receives he is at -1 to skill. Note it is possible with GURPS to use HP to power spells but since this damage reduces effective skill the whole process tends to be counterproductive.
==Keeping Wizards Different - Clerics and Magicians==
One of the biggest problems when different kinds of spellcasters share the same spell list is that they can have this annoying habit of blending into one another rather than being distinct. GURPS allows GMs to address this problem by providing enhancement and limitation modifiers to Magery.
===Ritual Magic===
Ritual Magic is ideal for Magicians as it is not only a (±0%) enhancement/limitation but uses a different mechanic giving it a different "feel". Ritual Magic's strength come from the fact spells are techniques defaulting to the college itself based on the number of prerequisite. So knowing Air College-15 results in knowing Air Jet-12 (3 prerequisite), Ball of Lightning-7 (8 prerequisite), and so on. Of course any spell below skill 3 is uncastable until raised to at least 3 (Ideally wizards should refrain from trying to cast spells at 10 or below due to greater risk of back fire.)
===Power Investiture===
Power Investiture is effectively a modified form of MageryMagery (Functions as a Different Talent ±0%; Sanctity Replaces Mana: ±0%; No Zero-Level Requirement +10%; Inspired Learning +20%; No Spell Prerequisites +30%; Pact -10%; No Magic Item Sensitivity -20%; Limited spell list -30%) with the most important component being (Sanctity Replaces Mana: ±0%). Sanctity represents the power of a particular divine/infernal being's power in the area. So what is high sanctity to one deity may be low or even no sanctity to another even if the deities in question share the same sphere of influence.
Power Investiture also allows GMs a method of actually using ideas suggested in the Dragon articles "Clerics live by other rules"Dragon #92 (Dec 1984), "First, spread the faith", "The more, the merrier", and "For King and Country"Dragon #101 (Sept 1985). The idea that deities get something or even everything from their followers allows sanctity to be tied to the amount of belief there is for the deity in the area. Since sanctity is determined by belief one devout worshiper is ‘worth more’ then a 1,000 followers but conversely that one devout worshiper is more ‘vulnerable’ than 1,000 followers. 
In this context Power Investiture is not a “reward” to a cleric but rather an “investment” by the deity in the promotion of their worship (and therefore an increase in the deity’s power in a particular area). As the Cleric shows/provides more worshipers, intensifies their belief, and promotes correct behavior the area’s sanctity level increases which in turn encourages the deity to improve the cleric’s Power Investiture. Conversely the cleric that misbehaves too much or lets too many of his deity’s worshipers be converted or killed sees the area’s sanctity drop which in turn results in the deity cutting back on the level of Power Investiture power. If either sanctity or Power Investiture drops to zero then the cleric will unable to personally cast spells until he corrects the problem.
Since Power Investiture is an investment by a deity it means that they can use non-clerics (like Rangers and Paladins) to promote and increase their power base. Also some deities may become more demanding as they provide their clerics with greater power; for example behavior perfectly acceptable for a Power Investiture 1 Cleric of a codal deity maybe disdained at level 2, frowned at by level 3, and completely forbidden at level 4.
=== Clerical Investment and Power Investiture ===
A special distinction must be made between Clerical Investment and Power Investiture. Clerical Investment is the Cleric’s social position and has nothing to do with Power Investiture. In fact, it is the personality of the empowering deity rather than than the religion the cleric belongs to that will shape what is considered proper behavior by clerics. This really gets interesting if the religion says one thing but the deity has other ideas.
==Spellcasting==
In GURPS Fatigue whose based value is derived from Health (CON) is the exchange of spell casting magic. The more fatigue is put into a spell the more ‘powerful’ it is; however if Fatigue reaches 0 the character is at risk at collapsing unconscious (at -FP this is a given). 
Problem is if a combat lasts more than 10 turns a character normally spends at least (1 + encumbrance level) points of Fatigue. Normally Fatigue is recovered 1 pt every 10 minutes of rest though there is a spell (Recover Energy) that speeds this up as far as spells are concerned. Note rest means sitting still or sleeping not walking around. Here we have a simple reason why GURPS wizards as a general rule do not go directly into battle; it would use fatigue which could be used to power a spell instead.
However, it must be noted that in GURPS wizard means any spellcaster - regardless of the spells being used coming from being Blessed, Magery or Power Investiture. This would put a major crimp on the classes that normally cast spells and wear heavy armor like the Cleric and Paladin but there are three options to this. 
* Fit and Very Fit: Like the Armor Proficiency feats but instead of being able to move properly in the armor these advantages better model what armor training really was - getting use to the weight of armor. Fit replaces light and medium Armor Proficiency feats and doubles recovery rate, while Very Fit replaces the Heavy Armor Proficiency feat and adds halving of physical fatigue costs to Fit. 
* LightenM67 and Lighten BurdenM143 Spells: costly in terms of time and energy if you go for the 50% weight option as it makes all other spells will be cast at -1 and requires Recover Energy and a high skill level to make maintaining it practical. 
* Energy Reserve (spells): This is a special form of Fatigue that is only for spells and can function as the equivalent of preparing spells. By default it is recovered at the same rate as normal Fatigue and is effected by the Recover Energy spell. 
**This can be combined with either Divided Magery (spells within a college, -40%) or Hyperdivided Magery (single spells, -80%) to limit how much fatigue can be used.
**This can be combined with a variant of Hang Spell to allow wizards the ability to cast really huge spells via study or meditation. 
The most important things to pay attention to in preventing abuse is fatigue [energy] costs, range (a hex is 1 yd), prerequisites, and spell type limitations (like most non seek information spells can be cast only once per day). If a spell is being abused chances are that it is being played incorrectly. There is a quick reference spell sheet (M222-M237) which should always be at the GM’s fingertips to allow quick consulting if there is a problem.
It is important to note that GURPS not only has critical success and failure built into the system but they are on a sliding scale; in other words effective skill determines what die rolls are critical success and failures.
===GURPS 3d6 System===
The Hypertext d20 SDR goes over the implications of changing from a d20 to a 3d6. However the main different between GURPS' 3d6 System and that of the D&D 3d6 variant is one rolls low to succeed in GURPS. This results in this table:
3d6 	3-4	5 	6 	7 	8 	9 	10 	11 	12 	13 	14 	15 	16 	17 	18
Number of combinations	4 	6 	10 	15 	21 	25 	27 	27 	25 	21 	15 	10 	6 	3 	1
Single % 	1.9	2.8	4.6	6.9 	9.7 	11.6	12.5	12.5	11.6	9.7 	6.9 	4.6 	2.8 	1.4 	0.5
Cumulative % 	1.9	4.6	9.3	16.2	25.9	37.5	50.0	62.5	74.1	83.8	90.7	95.4	98.1	99.5	100
d20 	20 	20 	19 	17 	15 	12 	10 	8 	5 	3 	2 	1 	1 	1 	1
Another difference is GURPS has a sliding scale where critical successes and failures for the Success rollare based on effective skill. A roll of 17 and 18 always fails and only defense rolls can be tried on with an effectively skill below 3 (spells that can be dodged or blocked) 
Normal Critical Table
Modified Skill 	2 orless	3 	4 	5 	6 	7-14 	15 	16+
3d6 Critical Success	NR* 	3-4 	3-4 	3-4 	3-4 	3-4 	3-5	3-6
d20 Critical Success	NR* 	20 	20 	20 	20 	20 	20 	19-20
Critical Failure 	NR* 	13-18	14-18	15-18	16-18	17-18	20 	20
d20 Critical Failure	NR* 	1-4 	1-3 	1-2 	1 	1 	1 	1
* If a non defense roll is attempted it is an automatic failure though the roll tells it is a normal or critical failure. For defense of 1 a critical failure is 11 and 2 is 12. This works out to be 8 and 5 respectively on a d20.
Since D&D is a highly cinematic it is suggested that you extend the Critical Success section with one of these methods:
Cinematic Extended Critical Success Table
3d6 Critical Success 	3-7 	3-8 	3-9 	3-10 	3-11 	3-12 	3-13 	3-14 	3-15 	3-16
d20 Critical Success 	18-20 	15-20 	13-20 	10-20 	7-20 	5-20 	3-20 	2-20 	2-20 	2-20
Compendium IISkill Level 	20-24 	25-29 	30-34 	35+ 	NA 	NA 	NA 	NA 	NA 	NA
WildcardOpen-EndedSkill Level 	17 	18 	19 	20 	21 	22 	23 	24 	25 	26
WildcardSlow Open-EndedSkill Level 	18-19 	20-21 	22-23 	24-25 	26-27 	28-29 	30-31 	32-33 	34-35 	36-37
WildcardRelatively CriticalHalf-BonusSkill Level	Att+360 pt	Att+372 pt	Att+484 pt	Att+496 pt	Att+5108 pt	Att+5120 pt	Att+6132 pt	Att+6144 pt	Att+7156 pt	Att+7168 pt
WildcardRelatively CriticalBonusSkill Level 	Att+248 pt	Att+360 pt	Att+472 pt	Att+584 pt	Att+696 pt 	Att+7108 pt	Att+8120 pt	Att+9132 	Att+10144 	Att+11156
===Hitting with spells===
In GURPS there is an advantage and skill called Innate Attack. For our purposes the skill is our main concern as it is what is used with abilities or spells that are either beam, breath, gaze, or projectile. Note that for Innate Attack spells the wizard must make two rolls: one to see if the spell was cast and the other to hit the target. Enforce the default penalties and spell specific modifiers outlined in GURPS Magic because unlike their D&D equivalents these spells do not have a save for half damage option and magic resistance behaves differently.
===Resisting Spells===
Spells resistance is by a Quick Contest of skill where the amount makes the roll matters as much as the roll itself with ties going to the defender. The critical success, normal failure rules and the Rule of 16 which is designed to prevent high skill level wizards from overwhelming resistance rolls on living or sapient subjects all apply.
For people and monsters add only the relevant ability modifier to 10 (HT uses Fortitude, IQ/Per use Will, and DX uses Reflex) for saves. 
====Spells vs Target====
A wizard with effective Body of Air 18, resisted by HT casts it on a subject with HT 13 and rolls a 13 succeeding by 5. The target must roll a 8 or less to resist the spell. However if he tries to cast this spell on a living or sapient subject with a HT of 16 or less, he rolls against 16. If his subject has a HT of 17, he rolls against 17. And if his target has a HT of 18 or higher, he rolls against 18.Basic Set p 349
====Spell vs Spell====
Spells that counter other spells also use this mechanic and lose skill if they fail.
A wizard with effective Crystal Ball 20 is trying to see into a Scryguard 21 area. He rolls a 9 (succeeding by 11) and the Scryguard rolls an 11 (succeeding by 10); the wizard sees into the Scryguarded area and the Scyrguard spell drops to 20. However, if the wizard above had rolled 3 to 6 he would have seen into the Scryguard area automatically (it getting no defense roll) and it would have dropped to 20. Conversely if the Wizard had rolled a 10 with the Scryguard 21 rolling 11 he would not have seen into the area and the Scryguard would remain at 21.
====Magic Resistance====
Magic Resistance is the GURPS equivalent of Spell Resistance with several important differences. For regular GURPS spells it subtracts from the effective skill of the caster which can increase the chance of a backfire. In addition it provides bonuses to resisted spells (double for area spells). GURPS MR comes in two forms: regular (which cannot coexist with Magery) and improved (which can coexist with Magery) but, barring a special enhancement, neither form can be turned off so MR will interfere with all external spells helpful as well as harmful. Also if a non-regular spell is not resisted MR provides no benefits.
So a MR 5 being will incur a -5 skill penalty to any regular spell and if it can be resisted like Berserker they get a +5 to their resistance roll, but while a caster gets no penalty to an area spell like Terror the MR 5 being gets a +10 to resist it. A missile spell like Curse Missile incurs no penalty for the spell caster and is resisted at only +5.
==Spells or situations that can easily be abused.==
===Analyze Magic===
At first glance this spell combined with Magery’s innate magic item detection ability would seem to short circuit any mystery about magic items. Several things to remember with this spell - it can only identify one spell on one item at a time, it goes from weakest spell to most powerful, it will only identify spells the mage at least has heard of, and finally is very costly in terms of both time and energy.
===Draw Power===
If the GM has run across the Pyramid article More Power: A Spell That Can Change a World this spell looks like a major problem in that it allows wizards to access more fatigue than they know what to do with. In addition to the limitations talked about in the article the spell in 4e now requires a device to harness the power.[GURPS Magic|Magic]] p. 180 So you cannot directly cast the spell on a power source.
===Invisibility===
In GURPS the Invisibility spell allows one to fight while remaining invisible. At first glance this would seem to be a real problem as D&D considered fighting while invisible such a huge advantage. This is because D&D forgets about the senses of hearing and smell and just because something is invisible in normal light does not mean that it is invisible in the infrared or ultraviolet. Spells like like Fog, Rain, Frost, Hail, and Snow will form an outline about the invisible being though the GM must consider if these weather conditions are a help or a hinderance to spotting the invisible foe. Also from the wording Mage Sight seems to spot mages (but not non-mages) using the Invisibility spell. Then there is the GURPS skill Blind Fighting which negates nearly all the penalties one has dealing with an invisible foe. Note that noise decreases the success with Blind Fighting (generally -1 to -3 though an area devoid of all sound incurs the maximum -7).
==Changing the power level==
The easiest way to up the power level is let wizards get lots of fatigue points or up the mana/sanctity level to very high. The down side to these methods is that letting wizard have buckets of fatigue even if it is Spells Only results in wizards casting insanely huge low cost area spells. Very High Mana level makes magic more common decreasing the status of a wizard (though not mages) but makes backfires more likely. 
Unlimited Mana is another option but it has some problems as well. Its main problem is it does nothing for clerics and can result in really bad things happening if the mages get careless with how much magic they throw around and start making Calamity rolls on a regular basis. 
Wild Mana is even more of double edged sword than Very High Mana as wizards can cast spells with no energy cost (rather than it being renews the next turn)...if they succeed. If they fail they have to come up with the full energy (Fatigue and Health if needed) and roll on the Critical Spell Failure Table. Natural critical failures under either Very High or Wild Mana are nearly alwaysThe Stable Casting (+40%) enhancement can be used to mitigate this to a large extent spectacular disasters.
D&D magic closest GURPS equivalent is a combination of Raw Magic (also known as Pure Mana)"All magic and cleric spells are similar in that the word sounds, when combined into whatever patterns are applicable, are charged with energy from the Positive or Negative Material Plane. (...) The triggering action draws power from some plane of the multiverse" DMG1 pg 40. which is five times more potent than any other form of mana with the Spell Slot system outlined in GURPS ThaumatologyGURPS Thaumatology p 56 As such GMs must e very careful in using Pure Mana as is makes GURPS wizards totally beasts in terms of power.
Another alternative is to combine the Ritual Magic concepts and allow wizards to draw power from the spirits they call on rather than the mana around them. This could be handled by a reaction roll on how the spirit viewed the spell being cast as per the Slayers anime; on a favorable reaction roll Lend Energy is cast by the spirit. The problem here is if the spirits have loads of fatigue they eagerly lend out your wizards suddenly become Lina Inverse Jr and can lay waste to large hunks of the countryside.
A fourth alternative is making Powerstones and Paut Talismans more available. Their base cost is based on a TL average starting wealth:
TL 	1 	2 	3 	4 	5 	6 	7 	8 	9 	10 	11 	12
Starting Wealth	$500	$750 	$1k 	$2k 	$5k 	$10k 	$15k	$20k 	$30k	$50k 	$75k	$100k
Material Cost
(1/100)	$5 	$7.50	$10 	$20 	$50 	$100 	$150	$200 	$300	$500 	$750	$1000
Retail Cost
(1/30)	$16⅔	$25 	$33⅓	$66⅔	$166⅔	$333⅓	$500	$666⅔	$10k	$16⅔k	$25k	$33⅓k
Up With Magic! Down With Magic! (Roleplayer #24, June 1991) give more ideas.
==Magic Items==
Without Industrial Enchantment powerful magic items (or items with many spells) will tend to be rare due to how the enchantment of items works in GURPS. It should be noted that Holy Objects are limited to followers of that particular deity making them more limited then their D&D equivalents. Building D&D Magic Items in GURPS goes into the various tools and concepts that are available to the GURPS GM.
==General Concepts==
*The Four Universal Types of Magic Systems - Hard/Soft; Nebulous/Rational
*Types of Magic Part 2: An Analysis of 7 Popular Magic Systems
==Notes==
==References==
Category:Adaptations
Category:D&D to GURPS
Category:Concepts
Category:Dungeon Fantasy