pf2e.fyi
From Pathfinder Impossible Magic, which isn't enabled.

Advanced Synergy

FEAT 6
ARCHETYPE
Archetype Summoner
Prerequisites Basic Synergy

You gain one summoner feat. For the purpose of meeting its prerequisites, your summoner level is equal to half your character level.

Special You can select this feat more than once. Each time you select it, you gain another summoner feat.
Pathfinder Impossible MagicORC