Grimoire Magic

Grimoires are eclectic tomes of eldritch, occult, or perhaps divine or forbidden secrets. Each such volume contains—among conflicting lore, obtuse diagrams, ambiguous scribbles, and the odd helpful note—a ritual to pay daily obeisance to the progenitor or patron of the book, a minor power known as a cantrip, and several initially unreadable, reality-bending spells. In fact, none of it is decipherable at all, unless one possesses the Grimoire Magic power.

Anatomy of a Grimoire

Ritual

Describes a way to please whoever originally offered up this mighty knowledge in manuscript form. It usually takes 1 hour to perform, can involve multiple participants, and may be attempted once per day. Affects the miscast chance and the cantrip. Roll Mind:

Critical Failure. As Failure, plus an effect dependent on the ritual.
Failure. Poor performance, displeased spirit. Take 1d4 Mind or Graces (your choice) damage.
Partial Success. Perfunctory display. Take 1 point of Mind or Graces (your choice) damage. Unlock the cantrip for the day.
Success. Unlock the cantrip for the day, and halve miscast chances from the tome’s spells.
Critical Success. As Success, plus reveal a new random spell from the book, or teach an already revealed spell to a participating ritualist (counts as a 1 slot gift whose use requires performing the grimoire ritual with the teacher).

Cantrip

Once a caster has at least partially successfully performed the grimoire ritual, they gain the power of the book's cantrip, a minor effect related to the tome's theme. They lose this power the next day, unless they successfully perform the ritual again. Requires the grimoire to be at hand.

Spells

The spells appear initially garbled and indecipherable, but a critical success on a daily ritual will permanently reveal one of them to the caster. Thereafter, they may cast this spell as often as they like, while wielding the grimoire. Each casting is dangerous however, and comes with a 28% miscast chance. A successful ritual performed that day halves this chance down to 14%. Special items, actions, or powers may reduce it further.

d4	Miscast Effect
1	The caster takes 1d4 Mind or Graces (GM’s choice) damage, and the casting fails.
2	The spell's effects are halved, or last only for a short period of time, or are otherwise limited.
3	The spell works but has unexpected side effects that could be beneficial now, but might cause issues later.
4	The spells effects are doubled, or affect a much bigger area than planned, or are otherwise exaggerated.