Isn't that what he wore in the Son of Batman movie?
Maybe Damian got the book for fix bigger things in the world just like he did about year of blood... and I still think he is going to learn magic... any chances of he trying to bring Alfred back?
For those who were wondering about the Black Casebook, here's an explanation from Grant Morrison
When will dick find him
They will meet in 'Tec #1032. Damian and Bruce will try to save Batfamily from Hush there, including Dick.