DARK SOULS 3 Quelana Pyromancy Tome Location

Found at Smouldering Lake: by the remains of a spider that resembles the Chaos Witch Quelaag from Dark Souls. Go thorugh an illusory wall in a room with three small rats

Give to Karla to unlock Fire Whip, Firestorm, Rapport

Found at Smouldering Lake: by the remains of a spider that resembles the "The Fair Lady" from Dark Souls. Go through an illusory wall in a room with three small rats.
From the Demon Ruins, turn around and head down the stairs. Once at the bottom of the stairs, there will be an open room, forward and to the right in another set to stairs down. At the bottom of these stairs, there is a flaming orb, go to your right, and all the way to the end of the hall, there is a door on the right. Down this hall way will be a rat, and before him is another door on your right. Go through that door, and the illusory wall will be directly in front of you.