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

Halcyon Spellcasting Adept

FEAT 14
ARCHETYPE
Archetype Halcyon Speaker
Prerequisites Halcyon Spellcasting Initiate; master in either Arcana or Nature and expert in the other

You refine your halcyon magic. You gain two common 4th-rank halcyon spells and two 5th-rank halcyon spells. You also gain a 4th-rank halcyon spell slot and a 5th-rank halcyon spell slot. Your proficiency rank in either arcane or primal spell DCs and spell attack rolls advances from trained to expert.

Pathfinder Lost Omens Character GuideOGL