Magic Explained! Q&A on GURPS Magic and Grimoire

by Sean "Dr. Kromm" Punch

Art by Kirk Reinert and Peter Scanlan

What follows is a number of clarifications and answers to questions about the GURPS magic system, including specific spells from Magic and Grimoire. These questions were originally posed on the Internet, and have been edited here for clarity and brevity, and to preserve context. Feel free to send your questions to Dr. Kromm.

Magic Explained! Q&A on GURPS Magic and Grimoire

Casting Spells

Casting Time

1. Is the following illegal:

Turn 1: Start casting spell A (casting time 1 second).
Turn 2: Roll for spell A. Cast and roll for spell B (which I know well enough that its casting time is 0). Cast a Blocking spell.
If so, why?

2. I have always considered the roll at the beginning of Turn 2 to be there for timing purposes only. Is this correct?

-- Steven Burrows

1. That is illegal. You're casting three spells on Turn 2. "Casting" means "rolling the dice for a spell." You may do that once per turn, normally -- twice, if you cast a Blocking spell. In other words, on any one turn, the effects of no more than one spell (other than a Blocking spell) may commence. With the correct terminology and rules, your example would be:

Turn 1: Concentrate on spell A (1 turn).
Turn 2: Cast spell A. Cast Blocking spell.

If you have a zero-time spell, then a better sequence of events would be:

Turn 1: Cast spell B (no casting time). Concentrate on spell A (1 turn).
Turn 2: Cast spell A. Cast Blocking spell.

2. No. It's there because that's when you cast the spell and the spell effects appear. It is a safe assumption that if a single mage causes two sets of spell effects to appear in one turn, the rules have been broken (unless one of the spells is a Blocking spell).

Energy Cost

If a spell allows one to pay double the energy cost for an enhanced effect (such as Create Mount, which can create a War mount at double cost), the doubling is done before any reductions for high skill come into play, right?

-- Harold Carmer

Yes. Energy reductions for high skill are always applied to the final cost of a spell, after all energy cost multipliers (for area, enhanced effect, et cetera) have been applied.

Ceremonial Magic

Regarding spectators and ceremonial castings: Can a spectator simply be indifferent? Or must he/she be emotionally invested in the casting to affect it's outcome?

-- Nathaniel P. Eliot

Spectators must personally believe in and feel strongly about the outcome (positive or negative) of a ceremonial casting in order to have any effect on the fatigue available. You can't just corral a bunch of beggars into your courtyard and order them to help, for instance.


1. What makes a circle? You need one mage to act as the caster. That is obvious. What is needed to qualify as the second person?

2. Most (if not all) of the following can contribute some energy toward a ceremonial casting. Which of them wouldn't qualify to join a circle:

(a) A mage who knows the spell, but not at level 15?
(b) A non-mage who knows the spell at level 15 or better?
(c) A sun-aspected mage who knows the spell at level 35 when you are trying to cast the spell in Alaska, at midnight, on December 21st?
(d) A one-college mage, from a different college than the spell being cast, who knows the spell at 15 or better?
(e) An unskilled observer who wants the spell to happen?
(f) An unskilled observer who is opposed to the spell?

3. Can you use extra, well-disposed spectators to make up for a few malcontents who are opposed to the spell?

4. Can you ever get negative energy because you have too many malcontents?

5. Stated another way, when is the limit of +100 or -100 fatigue applied?

6. Does it take a conscious decision to be a spectator who is opposed to the spell?

7. If someone had a disadvantage such as Manaphobia or Intolerance of mystics, would he count as opposed, even if he didn't understand what was happening?

8. What if he knew that it was a spell, but didn't know anything more specific than that?

9. In GURPS Magic, it states that all spells in the Enchantment college are cast using ceremonial magic. So why do the examples for both "Quick & Dirty" and "Slow & Sure" enchantment give examples of one mage creating a magical item? Is this supposed to be an exception to the normal ceremonial magic rules, or is it an error?

-- Bret Indrelee

1. Any mage who knows the spell at all, and any non-mage who knows the spell at 15 or better, may join the circle.

2. Only (e) and (f) wouldn't qualify as members of the circle. As spectators, they can only affect the amount of energy available.

3. Yes. The limit is on the number of energy points one can gain (or lose) due to spectators, not on the number of spectators.

4. Definitely!

5. Take any number of spectators. Add 1 energy to the sum for each well-meaning one. Subtract 5 energy from the sum for each one opposing the spell. The final sum must fall in the range -100 to 100. EXAMPLE: If you have 666 spectators, of which 561 are friendly and 105 are opposed, you have 561 -(5 x 105)=36 energy available. If you add another 75 friendly spectators, you have 100 energy available, not 111.

6. Yes. The spectator must actively oppose the casting.

7. If such a character gave in to his disadvantage, he would count as opposed. Good roleplaying would be for him to simply flee the ritual, or disrupt it with preaching, heckling and so on.

8. If he suffers from manaphobia, he doesn't care what the spell is! He just fears magic, period.

9. Inasmuch as the Enchantment spells can only be cast in a lengthy, ritual form, they are cast "ceremonially." All that statement really means is that enchantments are always full-length rituals, never fast-casting spells that can have cost and casting time reduced for skill.


1. Can a single caster ever trade power for skill (which is only possible during ceremonial magic, if I recall correctly)?

2. Why are two or more casters required? I see no problem with one caster performing ceremonial magic.

-- Stefan Leng

1. A lone caster can never trade power for skill.

2. The justifications given for ceremonial magic are that it allows other mages to help the caster (p. M14) and that a group aids concentration (p. M15). These would seem to be the reasons why lone casters cannot perform ceremonial magic.

Extra Effort and Magic

When casting damaging spells (such as Fireball), can a mage use some sort of extra effort or added fatigue cost to increase the range, area or damage of the spell?

-- Runar Magnusson

There are no printed rules for this. You could certainly choose to allow it if you wish. Use GURPS Psionics as your guide: Each extra level of effect (e.g., die of damage) would cost the normal amount of fatigue, plus 3 additional points for the extra effort, and would give -2 to skill. EXAMPLE: A mage with Fireball-18 creates a 5d fireball. This costs 5 fatigue for the spell (1 point per die), plus 6 more for the extra effort (two levels of extra effort, at 3 points each), -1 for his high skill, for a total of 10 points. He is at -4 for two levels of extra effort, and rolls at skill 14.

Limited Magery

Does a Star-Aspected mage need to learn his spells by candlelight?

-- Bret Indrelee



A One-College Mage should be able to learn and cast Lend ST if he can learn and cast Recover ST. Yes?

-- John Jackson


Mana Level

Long-Distance Spells and Mana Boundaries

I want to cast a divination from Al-Haz and across Caithness (which has low mana) to target something in Zarak. Would that be at -5 or normal? If it is at -5, could that be avoided by making the spell take a longer route around (or under or above) the low-mana zone?

-- Nathaniel P Eliot

If the spell crosses a low-mana region, it is cast at -5. You can choose whatever path you want for the spell, though. A straight line is normally preferable, because it results in the smallest distance modifiers; however, if that line crosses a zone of low (or no) mana, it may be to your benefit to trace a less-direct route through regions of higher mana level. Keep in mind that this will increase the distance penalty! The same rule can be applied to the Teleport spell.


In an old Roleplayer Q&A, it was stated that you use the worst mana level (caster or subject) to determine any penalties. I assume this would apply to divinations, so if you cast Seeker on someone in a low-mana area, you would have an additional -5 penalty.

-- Bret Indrelee

Yes. That is correct.

Regular Spells and Mana Boundaries

Magic cannot traverse areas without mana, but if the caster and the subject are both in areas with mana, can the spell travel around an intervening no-mana zone?

-- Ulf Andersson

Yes. A spell always travels from caster to subject via the shortest route that contains mana. If any part of that route is in a low-mana area, there is a -5 to skill; if there are multiple routes, then the one with the lowest total skill penalty (for distance and mana) will be taken. Distance penalties are figured based on the actual path taken, not on the straight-line distance from caster to subject. This means that a caster can affect a subject who is separated from her by a no-mana zone (NMZ) if her skill is high enough to absorb the penalties for casting around it. One implication of this rule is that mages can cast spells over the NMZs created by the Drain Mana spell (with an increased range penalty, of course), since these extend only 4 yards up. In all cases, if either the caster or the subject are in a NMZ, no spell can be cast.

Very-high Mana and Recovering Strength

1. Magic tells me that in very-high mana (VHM), the energy spent by mages is renewed every turn! Is this correct?

2. Does this mean that a mage can recover all fatigue, regardless of its origin?

3. If a mage casts a spell and then spends a point of fatigue to end it prematurely, is that renewed immediately?

-- David Pidcock

1. More or less! Energy returns at the beginning of the turn after it is spent, so you have to have the energy to spend it. If you want to cast a 1,000-energy spell, you still have to have 1,000 energy available.

2. No. Only that portion of the mage's personal ST that is used to cast spells is restored in VHM, not fatigue from psi use, sword swinging or stun weapons, nor HT or Powerstone fatigue used to cast spells.

3. No. That's treated as normal, physical fatigue. It's not reduced for high skill, so it's not really a magical energy cost at all.

Magic Explained! Q&A on GURPS Magic and Grimoire


Am I correct in assuming there is a difference between Magery as a prerequisite and spells as prerequisites? Anyone can learn the mechanics of any spell if they know all the spell prerequisites, even if they can't meet the Magery prerequisites, right?

-- Gerald Grenier

No. Anything listed on the "Prerequisites" line for a spell is absolutely required to be able to learn the spell at all; see p. M5. The issue of whether you can cast a spell that you have learned is a completely separate one -- this generally requires either Magery or a "high" or better mana level. In other words, a spell without Magery in its prerequisite chain can be learned by anyone, but can only be cast by a mage unless the mana level is "high" or better; a spell with Magery in its prerequisite chain can only ever be learned or cast by a mage.

Specific Spells

Animate Machine, p. G98

What is the cost to maintain this spell?

-- Aerron Winsor

Half the cost to cast.

Create Plant, p. M75

Can the Create Plant spell be used to create bush-sized trees for 8 points? Or tiny rose bushes for 4 points?

-- Aerron Winsor

Yes. The energy cost is keyed to the size of the plant(s) created. Don't get hung up on semantic issues like, "What is a bush and what is a tree?"

Draw Power, p. G101

Can this spell be taken at TL3 and used to draw power from water wheels, et cetera? What about at TL4?

-- Aerron Winsor

Yes. Draw Power/TLx can be used at no penalty on any power source built at TLx.

Powerstone, p. M47

A mage is making a Powerstone. He casts Powerstone repeatedly at skill 16. If one roll is a critical success that raises the Power to 20 (as a result of the critical success rules in GURPS Magic), what is the Power level of the Powerstone? Is all but one point of energy at Power 16? Or is the whole Powerstone at Power 20?

-- Harold Carmer

If Power gets boosted by 2d levels by a critical success (as per p. M18), then the whole Powerstone gains in Power. In this example, it would be Power 20. This is sort of like a "positive quirk."

Radio Hearing, p. G102

If a mage has cast Accelerate Time and Radio Hearing, can he hear compressed broadcasts coming from outside the area of the Accelerate Time spell?

-- Aerron Winsor

Yes. Slow Time "red shifts" signals going out, so Accelerate Time should "red shift" signals coming in. This would allow a compressed signal to be more easily interpreted.

Recover Strength, p. M49

It seems as though Recover Strength should speed recovery from all forms of fatigue, not just magical spell casting. Is this correct?

-- Harold Carmer

Yes. Recover Strength can restore any ST loss that could normally be recovered by sitting and resting quietly. This includes fatigue due to spell casting, psi use and most forms of exertion, but not that due to dehydration, missed sleep, starvation, or extreme heat or cold, nor ST lost to attacks (drugs, spells, weapons, et cetera) that lower ST for a fixed duration.

Seek Machine, p. G95

1. Is a TL4 mage at a -5 penalty to find "the nearest machine" when the nearest machine is a TL5 steam engine?

2. If the machine is in a no-mana area, can it be found?

-- Aerron Winsor

1. Yes. Any spell with a /TL takes normal TL penalties when it has to interact with a higher-TL machine. A TL4 tech-mage is at -5/-10/-15 to deal with TL5/6/7 machines, and cannot use his spells on TL8+ machines at all.

2. No. No Information spell can look into an area without mana.

Watchdog, p. M77

1. The Watchdog spell detects hostile intent. Is this "hostile to the caster," or is it any hostile intent at all?

2. What if the person crossing the spell's edge is hostile to the caster, but doesn't know he is there?

3. Is theft considered "hostile"?

-- Aerron Winsor

1. Hostile to the caster.

2. That doesn't matter. If, upon discovering the mage, the trespasser would react in a hostile manner, the spell will detect him.

3. Yes. Theft, injury, vandalism, casting baneful spells and hollering insults are all are hostile activities for the purpose of this spell.

Article publication date: August 13, 1999

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