Wizard do not normally use spell skills. They use spell slots. To gain a spell slot, buy Modular Memory with the Super Memorization, Spells Only, Limited Use (once per day), and Preparation Required (1 hour) limitations.
The cost for a slot is 1 + 0.6*point cost for the skill level of the slot. A spell slot must provide at least IQ+0. Therefore, the minimum for a Hard spell slot is 1+0.6*4 = 4, and for a Very-Hard spell slot, the minimum is 1+0.6*8 = 6. As normal, all fractions are rounded up.
- A spell slot for a Hard spell at IQ+3 is 1+0.6*16 = 1+ 9.6 = 10.6 11 points
- A spell slot for a Very Hard spell at IQ+4 is 1+0.6*24 = 1 + 14.4 = 15.4 16 points
To cast a spell all IQ and Magery prerequisites must be met. Spells found in books are provided as-is, and all spell prerequisites are assumed to be integrated into the spell. However, to research a new spell, the wizard must have access to all prerequisite spells for that spell.
These spells are prepared from a spell book. As “arcane” casters, Wizards may not use spells that are only in the Animal, Plant, or Healing schools, unless they are a prerequisite for another wizard spell. If a spell in one of these school is cross-listed under a school the wizard does have access to, then the spell may be learned under that school.
Wizards do not acquire new spells using build points. New spells are acquired by purchasing them from some vendor (another wizard or a magic supply shop), as adventuring loot, or through research.
Spell Mastery: If a wizard has a spell, and all of its prerequisites in their spell book, and is able to cast that spell, they may learn that spell as a Very Hard spell skill (as per the “normal” GURPS rules). The cost for the initial purchase of this skill is 1 + minimum number of prerequisite spells. GURPS Thaumatology provides a table of the minimum number of prerequisite spells. This initial cost replaces the normal 1-point cost of buying a skill. This skill can be increased for the normal price. For example, Explosive Fireball has a minimum prerequisite count of 4, so it would cost 5 points to buy at IQ-3 (assuming that this wizard’s spellbook also contains Fireball, Create Fire, Shape Fire and either Ignite Fire or Seek Fire, and that the wizard has Magery 1, which is required for Fireball). To increase from IQ-3 to IQ-2 will cost 1 extra point. To increase from IQ-2 to IQ-1 will cost 2 more point; from IQ-1 to IQ+0 is an additional 4. So, to buy Explosive Fireball as a spell skill at IQ+0 will cost a total of 12 points (5 to purchase plus 1+2+4).
Researching a new spell is done via the New Invention rules (BR p.473), using the Thaumatology skill as the “invention skill”. Simple complexity spells are those with no prerequisites, or only Magery 0 as a prerequisite. Simple complexity spells are those that have at most Magery 1 as a prerequisite, or where the highest Magery requirement for any prerequisite spell is Magery 1 or less. Complex spells are those with a Magery 2 prerequisite, or where the highest Magery requirement for any prerequisite spell is Magery 2 or less. Amazing complexity is for all other spells.
For wizards, there is a penalty to the casting check equal to double the encumbrance penalty. Buy Magery at +50% to reduce this halve this to this penalty. Buy Magery at +80% to eliminate this penalty.