Resonance spells are a special type of spell attained from one's attunement to a Harmony. You can learn resonance spells only through special class features or feats, rather than choosing them from a spell list. Furthermore, you cast resonance spells using a special pool of Resonance—you can't prepare a resonance spell in a spell slot or use your spell slots to cast resonance spells; similarly, you can't spend your Resonance to cast spells that aren't resonance spells. The title of a resonance spell's stat block says “Resonance” instead of “Spell”, and the spell has the choral trait.
Resonance spells are automatically heightened to half your level rounded up, just like cantrips are. You can't cast a resonance spell if its minimum rank is greater than half your level rounded up, even if you somehow gain access to it.
Casting any of your resonance spells costs you 1 Resonance. You gain a Resonance pool the first time you gain access to a resonance spell. The maximum number of points in your pool is equal to the number of resonance spells you know or 3, whichever is lower. This counts only spells that require Resonance to cast.
Resonance cantrips cost nothing to cast, but require that you have a Resonance pool. Resonance cantrips do not contribute to the total number of Resonance you can store in your pool.
You replenish all the Resonance in your pool during your daily preparations. You can also use the Refocus activity to listen to your Harmony and regain 1 Resonance. You can Refocus multiple times to regain multiple Resonance, up to your pool's maximum.
Your resonance spells are the same tradition as the Harmony that granted them. If a Harmony has multiple traditions, you may select one tradition to apply to all resonance spells you know. You may change your selection when you level up. The Voidsong is both Divine and Occult.