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From Pathfinder Lost Omens Character Guide, which isn't enabled.

Halcyon Spellcasting Sage

FEAT 18
Archetype Halcyon Speaker
Prerequisites Halcyon Spellcasting Adept; legendary in either Arcana or Nature and master in the other

Your command over halcyon magic is nearly unmatched. You gain two common 6th-rank and 7th-rank halcyon spells. You also gain a 6th-rank halcyon spell slot and a 7th-rank halcyon spell slot. Your proficiency rank in either arcane or primal spell DCs and spell attack rolls advances from expert to master.

Pathfinder Lost Omens Character GuideOGL