Secret scroll of the Profaned Capital court sorcerers, containing sorceries of Logan.
Give to a sorcerer to learn Logan's sorceries.
The court sorcerers used this scroll to claim heirship to Logan's legacy, though how that claim stands up to closer scrutiny is another story.
Dropped from Unkindled Apprentice in Profaned Capital. From the Profaned Capital bonfire, go down the interior ladder, through the broken wall, turn to the left and enter the tunnel. Proceed through the toxic swamp to a building with a ladder, climb up to the top of the building. On the roof is the enemy, kill it to get the scroll.