This is another fight where a reliable shield is a must. The gargoyles will come to life one by one; at most you'll be fighting four at the same time. Keep moving and avoid getting surrounded. These enemies are weak to lightning so Clerics with good shields will have an advantage since they can damage the gargoyles at a distance. Ranged characters won't have problems either since they can keep distance and land a hit or two before running away again. Lock-on must be turned on and off in the course of the battle; this will ensure that you'll see your target while maintaining awareness with your surroundings.
Melee characters can use long-range melee weapons to damage multiple gargoyles. Since they're sharing the same life bar, this will deal a great amount of damage. Take out the gargoyles one by one to make your job easier. The gargoyles' fire breath attacks can be evaded and they'll be vulnerable when using this. Sometimes, the other gargoyles will get stuck by the fire breather so this is a good chance to pummel it with your ranged attacks and spells or rush towards it away from its line of fire and attack.
After the battle, loot the corpse near the edge of the roof to get a Soul of a Proud Knight. Go to the next tower and go downstairs. Loot the Southern Ritual Band from the chest then light up the bonfire.
Be careful before taking the ladder down. There's an invader there and several hounds. If you have ranged attacks, you can snipe them from the top of the ladder. Loot the corpse from the ground to get a Bastille Key and the corpse on the top of the ledge to get an Enchanted Falchion.
The Bastille Key is required to open the locked door at the base of the stairs outside, along the path from the first bonfire (Exile Holding Cells) leading to the Sentinel Boss area. Opening this gate will lead you to a chests containing Large Titanite Shard x2, Titanite Shard x5, Iron Arrow x10, Heavy Bolt x10, McDuff himself and McDuff's Workshop bonfire. McDuff is a merchant; however, you need to give him a Dull Ember to open up his shop. This item is found in the Iron Keep.