No Default

No Default is explained on B344 under Default Rolls.

Magic

The hard ban on magic spells having no default is loosened in a some ways:

Techniques

Basic Set involves a Ritual Magery option to use spells as techniques of "Path" skills that default to a core skill. The initial penalty of the techniques was equal to the prerequisite chain count.

Spells defaulting to spells

GURPS Thaumatology pg 38 introduces a Spell Defaults option for Standard Magery but with the drawback of it taking double the energy and time

• Since this is STILL an upgrade, if it's not a standard rule but something only certain mages can do, the Improvised Magic perk in Magical Styles was introduced to represent that

Spells defaulting to IQ

Magical Styles' introduction of Wizardly Dabbler based on Dabbler effectively insinuates (though does not RAW state) that first-tier spells can default to IQ: due to getting 8 spells at IQ-6 this basically implies that the default for all 1st level spells would be IQ-7 since that is how Dabbler normally works.

• Like with Spell Defaults there is a built-in penalty for balance: even if IQ+Magery raises this above 9, it still counts as "9 or less" for ritual/cost/time
  • as this is no penalty at all for those not 10+, although it does not say to do so, since this is essentially a "boosted default" (ie "you don't truly know these spells") it would probably also make sense to apply the x2 energy x2 time penalty that spell Defaults / Improvised Magic uses

College Incompetence sort of hints at this too. Traditionally the Incompetence quirk only applies to skills you could know at default: it's not just a ban on buying the skill but a -4 to the default. As such it would only make sense to Ritual Magic's paths unless Standard Magery also had defaults.

Magery

Magery 0 is defined on B66. It would probably be easier to call it something else like "Mageness" since it has a different cost and different effects than the subsequent levels that function like talents. The most significant aspect of Magery is it's requirement in Basic Set to cast spells in Normal or Low Mana: with non-mages and mages having equal spellcasting ability in High Mana. A 2nd benefit in Very High Mana per B235 is mages who spend FP on spells get a refund the next second (doesn't appear to Burning HP, unclear if it would apply to Energy Reserve or not.

as a metatrait

Total Spell Incompetence on T22:

• Someone like this gains only the basic ability to sense magic items and changes in local mana level (see GURPS Magic), his Magery level as a bonus to his Thaumatology skill, and an aura resembling that of a mage.

There is really no discernible reason that someone would take TSI on Magery 1+. The primary benefits of TSI are received at 0: sensing items/mana and having a special aura. The only benefit seems to be getting a bonus to thaumatology. -60% to 10/level is 4/level which is the maximum cost of increasing a skill anyway, so it's pointless.

Having an aura resembling a mage actually appears to be viewed as a drawback. T29 for example considers it an enhancement to have an aura that doesn't detect as magic, or to be able to switch off magery to avoid detection. So it could actually be viewed as a sort of temporary disadvantage built into magery.

Representing TSI as Detect (B48) is suggested as "often a better choice". Magery 0 only gives 2 rolls: "first see" and "first touch" of magic items. B66 doesn't explain the mana level perception. The "Mana" box on B235 was expanded on page 6 of GURPS Magic with the addition of Sensing Mana at the bottom.

a balance note

Limited Magery 0 on T21:

• But what about those who can detect and use items but not cast spells while their limitations apply? Optionally, the GM may allow such mages to take limitations on Magery 0, but at half their usual value.

TSI is -60% (reducing 5 to 2) which would be half of taking -120% in advantages for Magery, as per Limited Magery 0. This probably assumes that people will not stack different limitations for magery to exceed that. B66 for example stacking Dance (-40) and Day-Aspected (-40) and Song (-40) totals -120% and gives all the benefits of TSI fo the same cost PLUS the ability to cast spells while singing+dancing in the day.

• This is probably due to magery limitations functioning like Accessibility which don't have a linear value between the % of time they apply and the % discount. PU8p4 for example assigns -40% for 1-6% of the time and -35% for 7-18% of the time. -5% is a lot for the jump from 6% to 7% but seems like little for jumping 1>7 or 6>18 or 1>18. The midpoints of 3.5 and 12.5 are 9 apart. Pg5 is even more extreme: 1 in 100 million is worth -70% while 1 in 1 million is worth -60%. This factor of x100 per -10% is also seen between 10,000 (-50%) and 1 million. That "1 person" is worth -80% implies there are 10 billion people.
  • This especially makes sense in cases where factors overlap. Dance+Song for example both impede stealth, Night-Aspected and Dark-Aspected would be convenient to have together.

partial

Continuous Mana on T58 introduces this option:

An interesting alternative is to let non-mages attempt to cast spells anywhere, but at -6.

There is a note under path/book to allow 5 degrees of Magery 0 to buy off the -5 penalty for non-casters (1 less bad than normal)

This could make "Mageness" be viewed as a leveled trait (max 5) for buying off a default penalty, with "Mageness 5" being equivalent to Magery 0.

In that case though it would probably make sense to not give sensing abilities built into magery since those weirdly come all at once on the 5th level of Mageness as a free benefit.

For it to make sense with tiered costs, the sensation abilities should be present at lower levels, but probably with progressively worse penalties.

-6 doesn't divide into 5 levels very well, it might work better as something like a 3-leveled perk buying off penalties in -2 increments, while the remaining 2 points buys the sensing abilities (as according to TSI)