Fixed Magic

Cost: Variable
Called knacks in Classic this was reworked in 4e as Fixed Magic and is calculated as an Meta-Trait Advantage.
4e addresses this on page 161 of GURPS Fantasy and it seems to be more costly than Racial Magic.
GURPS Thaumatology provides more options and changes how Magery 0 would be priced under this mechanic.
==Method for Figuring Cost==
# Total up prerequisites (each one costs 1 point)
# use the minimum level of One-Spell Magery required for the highest spell (round up)
# Calculate the cost of the spell if bought normally
==GURPS Fantasy Example==
*A Medic with IQ 11 has the innate ability to cast Minor Healing as skill level 12.
*For step one this is 2 points
*Magery 0 is 5 points (limitations normally aren't applied to this level of Magery) with One-Spell Magery 1 being 2 points more for a total of 7 points.
*For IQ + Magery to equal 12, 4 points are needed
*The grand total is 13 points.
==Potential Problems==
===More "Regular" Mages===
A savvy person can easily spot the problem with this method: it allows anyone with Fixed Magic to learn every spell in the game world that only requires Magery 0 as well have having the magic detection ability of the advantage (because Magery 0 itself isn't limited)
For the GM who doesn't want this to happen get the magery normally and then apply the limitation modifier.GURPS Thaumatology pg 21 This will prevent creatures with Fixed Magic from learning a host of spells in a magic rich setting.
===Above "Average" Members===
Another issue is what does having above normal abilities do? Say an IQ 16 Magery 3 wizard becomes a vampire that has Charm-12 as part of its race template and the wizard doesn't know that spell. Does the Wizard cast Charm at 12 like other vampires of that "species" or does he cast it at the level the IQ 16 Magery 3 would give him?
===Overly Complicated===
Given the wide range of enhancements and limitations available this is needlessly involved. No Spell Prerequisites, +30% on Magery itself eliminates the whole count the prerequisites step.
==Alternatives==
Another way to do this is to see if there is an existing equivalent advantage and use Magical [-10%] and any relevant Limitations to make it reasonably similar to the target spell. If GURPS Update and GURPS Thaumatology are any guide this is the preferred method even if odds are it will be more expensive in terms of time and points. 
For the Medic example in GURPS Fantasy the Healing advantage is a close fit though in terms of damage it can heal it is between Minor and Great Healing.
===Streamlined Spell Method===
This uses the version of Racial Magic made viable by GURPS Thaumatology (and uses the changes in how Magery 0 works):
Spell: Great Healing
*Magery 3 (-50% :One-Spell Magery, -80%; No Spell Prerequisites, +30%) is [18]
*For IQ + Magery to equal 12, 2 points are needed
*The total is 20 points
Note per the spell this is limited to once per day per subject.
Call this Fixed Magery or Magery (Fixed). The cost of this based on the number of colleges in the setting is in the table below. The (-80%) on 30+ colleges for One-Spell Magery is because total limitations are capped at (-80%) - it actual value would be (-100%) or free at all levels. But this (-100%) is what must be used when enhancements are added.
Total Colleges in setting 	2 	3 to 2	7 to 14	15 to 30	30+
One-College Magery 	(-10%)	(-20%)	(-30%) 	(-40%) 	(-60%)
Limited Spell List Cost 	NA 	(-10%)	(-20%) 	(-30%) 	(-50%)
One-Spell Magery Base Cost	(-50%)	(-60%)	(-70%) 	(-80%) 	(-80%) cap(-100%) actual
Fixed Magery 	(-20%)	(-30%)	(-40%) 	(-50%) 	(-70%)
===Mimicking Classic Knacks ===
If one want to come close to mimicking the way Knacks worked in Classic one could use 
*Magery 2 (-55%: One-Spell Magery, -80%; No Spell Prerequisites, +30%; Inspired Learning: (+20%); No Magic Item Sensitivity, -20%; Costs fatigue (1 FP, -5%)) [12] and (adjusting One-Spell Magery accordingly +5% for each spell above one) buy up each spell to 15 using the race's IQ.
However, 
* Racial Magic (-40%: One-Spell Magery w/ 6 spells, -55%; No Spell Prerequisites, +30%; Inspired Learning, +20%; No Magic Item Sensitivity, -20%; Can't Use External Energy, -15%) 
works better in terms of not having to change the percentage value though it is over priced for 1-5 spells and under priced for 7 or more spells.
If one of the spells requires Magery 3 or 4 just use that for all the spells adjusting the relevant spells to 15 accordingly.
So an IQ 10 race with 1 (H), 1 (VH), 1 (H) Magery 3, and 1 (VH) Magery 3 (4 Knacks total) would be Magery 3 (Racial Magic-40%; Costs fatigue (1 FP, -5%); 4 spells, +15%) [21] + [12] + [16] + [12] + [16] or [77]
===Innate Magic (Advantage Method)===
*Healing (Magical [-10%] and Injuries Only [-20%]) [21]
The extra 5 points covers eliminating the once per day but the skill level is 11 not 12 so it is a bit of a trade off.
==Classic Version==
Acquired via Spellgraft per Designer's Notes: Bio-Tech (Pyramid Classic 29 sample)
==References==
*GURPS Fantasy pg 161
Category:Advantages
Category:Magic Systems
Category:Meta-Traits
Category:Classic Meta-Traits