Editing Macchiato Monsters: The Stygian Library (section)

====How spellcasting works for this game====
This amends and supersedes page 30 of Macchiato Monsters. The design goal is to reduce complexity while leaving the other systems that touch spellcasting intact.

*If you have spells, you can cast any of your known spells at any time. There's no memorization.
*Each spellcasting PC has one stat they use for all spellcasting: probably INT or WIS, maybe CHA. Pick one and consider what it means for your casting style. (INT suggests an arcanist studying magical effects of their own, WIS suggests channeling cosmic or divine forces, CHA suggests elevated illusions, tricks, music, or fast-talk.)
*Casting a spell takes your full round in combat, which is spent gesturing and speaking aloud. (If you're restrained or silenced, no casting.)
*When spells have a duration, the usual duration is a number of exploration turns (around ten minutes) equal to your level. Some spells (the description will say so) use the magician's sigil: this sigil takes one exploration turn to inscribe, and the associated spell is permanent until the magician casts it again, drawing a new sigil as the previous one fades.
*All spells have a cost of 3 HP. The cost can instead be spent with the result of your Reagent or Faith die in part or in full. You can't spend down to 0 HP.
*The first time you cast a spell in a situation (a scene, room, or combat,) you may roll your Reagent or Faith die (with risk of it stepping down on a 1-3 result) and note the result (for example, 4.) You can spend from that pool in spell costs for this situation before you start spending your own HP.
*When you cast a spell...
**If it's your first spell in this situation, first roll your Reagent or Faith die.
**Spend the cost (3), either from your Reagent or Faith pool or your HP.
**Roll an INT, WIS, or CHA check.
***On a success, at or under your stat, the spell works as described. On a critical success (a 1), you don't pay the cost.
***On a failure, the spell doesn't go off. On a critical fail (a 20), there's some mishap or danger.
***But! If the spell fails, you may roll what MM calls the Chaos Risk Die to make something happen anyway. This is a roll on a table where most results have the spell go off with a weaker or modified effect, and a few results harm you in a hurty but not deadly way. In this game, "invoking Chaos" only works within the Library (or possibly other magical sites) and represents drawing on the exhaust of its condensed arcane power, which can be expended as the Risk Die steps down and fizzles out.