after u beat the razzac u can go back and get the book but u have 2 have lvl 72 magic

get arya after you beat the raz'ac and ***ign all
of her focus to magic, then train in the spine until she has 76 magic focus
then you can get that book and the one in angela's house

brom's house= burn the sky
angela's house= silver rain

Its simple!You just have to get out of the village,level up and, when you have enough
magic,return to carvahal

after escaping from gil'ead w/ arya (***ign her points to magic) go to carvahall there are
many books in the forest, warehouse, and spine. to get some you may need to go to teirm w/
murtagh b4 rescuing arya and talk to the guy in the green robe. go rescue arya and below
her cell will be a man identical to the one in teirm. talk to him and he will follow you
out. then go 2 the spine and you will c another man where the box was on the west end of
the spine. talk and walk w/ the man and he will take u 2 the place saphira took u 2 in the
beginning. there are magic books and herbs galore in the forest and spine.

you have to get a level 72 magic focus and then read the book to get a powerful magic
spell from it.