Big Hat Logan
Big Hat Logan is a powerful sorcerer whose questline is intertwined with the player's journey. You first encounter him trapped within the confines of Sen's Fortress. Upon freeing him from his predicament, he will relocate his studies to the relative safety of Firelink Shrine. Later in your adventure, you will find him imprisoned once more, this time within the formidable Duke's Archives. Again, successfully liberating him will lead to him sharing his advanced sorceries with you. After you have purchased all the spells he has to offer, Logan succumbs to the corrupting influence of knowledge and goes mad, becoming a formidable, albeit tragic, encounter.
His madness transforms him into a hostile entity, and if you encounter him in the Duke's Archives after he has taught you his spells, he will attack. He wields powerful sorceries, including Crystal Soul Spear and Crystal Homing Soulmass, making him a significant threat. Defeating him in this state will yield his signature attire, the Big Hat, and his staff. His questline is crucial for obtaining some of the most potent sorceries in the game, but it requires careful management to avoid his descent into madness prematurely or to successfully defeat him when he does.
To progress his questline and acquire his spells, you must first find him in Sen's Fortress. After defeating the Iron Golem and ringing the second bell, he can be found in a cage. Freeing him allows him to move to Firelink Shrine. He will then offer a selection of sorceries. To find him again, you must reach the Duke's Archives. He is located in a cell, and freeing him again will unlock more powerful spells. It is important to note that if you progress too far into the Duke's Archives without freeing him, he may become hostile prematurely. His ultimate fate is tied to the player's actions and the progression of the game, often leading to a challenging boss fight if not handled with care.