Karla Dark Souls III Guide
Last update: 01 June 2016
Irithyll Dungeon
Note: To open the cell with Karla, you require Prison Guard's Keys. You can find them in Profaned Capital (you can find a detailed walkthrough for this section in chapter Profaned Capital - return to Irithyll Dungeon).
You can get into Karla's cell from the room below that is full of life-draining opponents. To fight with all of them at once, enter the chamber from the side of the bridge in Profaned Capital. Go into the corridor on the left and walk around the main cluster of enemies. Kill one of the guards and open the cell at the end. Inside, you find witch Karla - forgive her and she will teleport you to Firelink Shrine. She will then be able to teach dark magic to you and accept from you the books that Cornyx did not take, or you did not want to give them to Irina.
Firelink Shrine
You find Karla in Firelink Shrine in the recess below blacksmith Andre. She accepts books and teaches dark spells. You can give her the books that Cornyx refused to take (Quelana Pyromancy Tome and Grave Keeper's Pyromancy Tome). Additionally, she also accepts books that allow you to purchase dark miracles, which you also could have given to Irina (Braille Divine Deep Tome and Braille Divine Tome of Londor - try to give her the books twice).