Otherwise known as the casting handbook. Where players learn how spells work as practiced abilities on Nilgiri's skills tree — practice, apprenticeship, and casting — not immortal spell construction.
Spell definition tooling (@spell workspace) belongs to Creation Law. This page is the player side.
Nilgiri is classless. Natural stats at creation determine how far fundamentals (notably spellcraft and related mystic fundamentals) can be practiced; those gate primary spell practicals; those gate tertiary spells. Practice caps follow prerequisites on the Skills Tree Graph (Graphviz skills.png from ant SkillTreeGraph / skills.dat). Skills and spells share one graph; non-spell skills are covered under Skill Law.
Spellcraft is a gateway fundamental: its post-requisite list is the first wave of castable practicals (identify, teleport, armor, magic missile, and many others). Primary spell practicals require practiced fundamentals (for example armor needing spellcraft and psychokinetic). Tertiary spells require prior practicals at category minima (for example barrier needing armor at least Category IV / proficiency 31+; greater protection needing both protection-from-evil and protection-from-good at Category III).
Use practice <name> to see qualifiers, pre-requisites, maxima, and post-requisites before you spend sessions with learn.
Complete inventory of spells on the Skills Tree Graph. A practiced ability is a spell when it appears in the Spells enum (each bound to a Skills node). Classification matches SkillTree: primary spell practicals have a fundamental as first parent; tertiary spells have another practical as first parent. Non-spell skills are listed on Skill Law.
Counts: 43 primary spell practicals, 75 tertiary spells (118 spells on the tree).
First wave of castable practicals gated by mystic and related fundamentals (elementalism, catechism, animism, and combinations). Spellcraft itself primarily gates the device skills staves / wands / scrolls (see Skill Law); many castable primary spells hang from the other mystic fundamentals.
Spells gated by category thresholds on prior practicals (Skills type 2).