Mana powered Magic does not work on worlds with no mana but magic powered by other things (Sanctity or Psi) can. Note that Mana Enhancer changes this somewhat.
Very High ManaEdit
Anyone who knows spells can cast them. Very high mana worlds make magic common and more potent, affecting some rules. First, a mage who spends FP (Fatigue Points) to cast a spell on his turn gets those FP back at the start of his next turn. Second, all failures are treated as critical failures – and actual critical failures produce spectacular disasters!
Anyone who knows spells can cast them.
Only mages can cast spells. This is the default mana level in most fantasy settings: mages use magic, others don’t.
- see however Non-Mages Casting in Lower-Mana Areas
Only mages can cast spells. Low mana worlds make magic rare and less potent, affecting some rules. First, all spells perform at -5 to skill, for all purposes. Magic items are similarly affected; see Power of a Magic Item  Second, critical failures have mild effects or no effect at all.
Very Low ManaEdit
Only mages can cast spells. All spells perform at -10 to skill, for all purposes and magic items require a power of at least 25 to function. Costs an extra FP which must come from normal reserve, not energy reserve.
No one can use magic at all. Magic items do not function (but regain their powers when taken to an area with mana). This mana level occurs in isolated spots in magical worlds, but entire worlds can lack mana, making mana based magic use impossible. Such worlds have Category:No Mana as part of their category listings.
Special Forms of ManaEdit
Continuous Mana is where the gradation from very low mana to very high mana is more gradual going from -10 to +10 to skill.
Variable Mana is where the mana level of an area fluctuates such as in regards to the time of day, the season, or weather.
In an area of Wild Mana "any success on a spellcasting roll counts as a critical success, and costs 0 FP, while any failure is treated as a critical failure, with the spell’s full normal energy cost."
Twisted mana is so weird that it causes magic to behave in an unpredictable, even perverse way. Spells are cast at -2 in addition to any other penalties.
Spells cast in Mana of this type do not cause fatigue but instead are counted against a threshold total (default is 30). The spell that first brings the mage's tally over Threshold triggers a Calamity Check with a +1 on the 3d for every full five points by which Threshold has been exceeded. All spells cast once Threshold is reached trigger a Calamity Check. "Once per day, the mage's Tally is healed by an amount equal to his Recovery Rate (RR). The "default" RR score is 8, with recovery occurring at sunrise."
How mana influences spells crossing multiple zones is addressed in two areas...
Roleplayer #4, February 1987 http://www.sjgames.com/gurps/Roleplayer/RoleplayerQ-A/RoleplayerQA.html#anchor1158038
- (2) What happens if a missile spell is sent from an area of regular mana into an area of low mana?
- (2) Interesting question – may or may not be worth mentioning in the revised Fantasy Book. I rule that a missile spell cannot enter a NO MANA area, but is otherwise unaffected by crossing mana boundaries.
Roleplayer #20, June 1990 http://www.sjgames.com/gurps/Roleplayer/RoleplayerQ-A/RoleplayerQA.html#anchor1164591
- What happens to spells that cross the boundaries of mana areas? For instance, what happens to an Explosive Fireball entering a no-mana area? Can a person using the Great Voice spell be heard 200 yards away by a person in a no-mana zone? What is the effective skill of a mage in a normal-mana zone casting a Lend Language spell on someone in a no-mana zone? – Rick Malavasic
- A missile spell would continue across the boundary into a no-mana zone. No other spell or spell effect would cross into a no-mana zone.
- When a spell is cast between different zones, both of which contain mana, calculate penalties as for the lower of the two zones. Thus, if either the caster or the subject is in a low-mana zone, the roll will be at -5. In the case of a spell like Great Voice, in which the "target" of the spell is the speaker, the location of the listener(s) doesn't affect the spell, as long as they are not in a no-mana zone.
- A caster in a zone of very high mana has the benefit of fatigue-free casting (if he's a mage) and the problem that any failure will be very dangerous, regardless of where his subject is standing. – Steve Jackson
some spells can curve, missiles can't http://web.archive.org/web/20061014014359/www.krommnotes.org/krommmag.html
- Q If a mage casts a spell and spends a point of fatigue to end it prematurely, is this fatigue from spell casting? Is that renewed immediately in a Very High Mana zone?
- A No. That's physical fatigue. It's not reduced for high skill, so it's not really a "mana" cost at all.
- ↑ Basic Set, p. 481.
- ↑ GURPS Thaumatology 58
- ↑ GURPS Classic Magic pg 94
- ↑ GURPS Fantasy pg 43-45
- ↑ GURPS Thaumatology pg 59
- ↑ GURPS Thaumatology 76-80