Babylonia (7th Singularity): Abandoned City Babylon (Free Quest) is the best AP-saving & time-saving location to farm Yggdrasil Seed. You'll get around 5x Yggdrasil Seed by spending 200 AP.
Orleans (1st Singularity): Jula (Free Quest) is the first location you unlock to farm Yggdrasil Seed.
Rashoumon event (Ibaraki Douji event)
Murder at the Kogetsukan
Inheritance of Glory
FGO Reroll Tier List [5/11 updated!]
Device Transfer Guide
How to farm EXP cards & level fast
Best Craft Essence: Craft Essence Tier List
Talon of Chaos (Claw of Chaos)
Glassful Sweet Time (Glass Full Sweet Time)