7th Singularity Babylonia: Marshland free quest is the best AP-saving & time-saving location to farm Serpent Jewel. You'll get about 2~3x Serpent Jewel by spending 210AP.
Rashoumon event (Ibaraki Douji event)
Murder at the Kogetsukan
Inheritance of Glory
Best Craft Essence: Craft Essence Tier List
Saber
Heaven's Feel
EMIYA
Fionn mac Cumhaill
Scathach
Manga De Wakaru! FGO
Astolfo
Spartacus
Atlas Institute
Necromancy