Sub-Singularity I Shinjuku: Shinjuku 2-Choume free quest is the best AP & time saving location to farm Forbidden Page. You'll get about 3x Forbidden Page by spending 210AP.
4th Singularity London: Hyde Park is a location where you can farm both Forbidden Page and Evil Bone.
Here is a list of servants that need Forbidden Page to perform Ascension and Skill Up.
]Journey to the West Event Re-run
Hunting Quest Part 1
Fate/Accel Zero Order Advance Campaign
Fate/Accel Zero Order Event
Lostbelt No.1: Anastasia
5 Star Servants Tier List: Best Servants [4/13 updated!]
Best Servants [★4]: 4 Star Tier List
1-3 Star Servants Tier List
Best Craft Essence: Craft Essence Tier List
Ivan the Terrible (Ivan the Thunder Emperor)
FGO Reroll Tier List
Anastasia Nikolaevna Romanova
Irisviel (Dress of Heaven)
Ramesses II (Ozymandias)
Black Holy Grail (The Black Grail)
Talk on the Heated Sands
Nine-Headed Bull Demon King
Lunar Hot Springs