You can now complete the Heptermeron achievement by collecting 7 Books hidden throughout Nightfall Citadel.
Once you have collected a book, you can turn them in to the NPC Ariston. He is located in Nightfall Citadel.
Once you have collected them all, talk to him again:
You will get the Heptameron Book!
Right Click to read/add
Get your Achievement!
Magic Academy, next to the telescope
A Child’s Smile
Magic Airship (fly up or teleport up) on the table
Tears of Pharaoh
On the wall next to NPC Azora Starlight (Crystal Light Exchanger)
On the Alchemists table, in the Rosemason Hall NPC Rachel
At Sundown Theatre, on a bench seat
In the Mercury Marketplace, on the Food Dealer Counter. NPC Faye
Spring of Love
In Charlie’s Tavern, on a table, bottom floor