Belfry Luna

This area requires a Pharros Lockstone. You can find one in one of the prison cells in the lowest level of Sinner's Rise. The entrance is also conveniently located under the Servants' Quarters bonfire so you can travel there as necessary.

There's a non-hostile dwarf on the right which will offer you to join the Bell Keeper covenant if you exhaust his dialogue options. Continue upstairs and defeat the dark spirit Bell Keeper. Loot the Skeptic's Spice from the corpse as well.

Continue upstairs and find two more spirits. They hit hard so don't underestimate them. Climb up the ladder and you'll face more dark spirits, including a red one. Fortunately, there's a lot of room to run around. Don't let them hit you with their arrows since they're accurate and can fire quickly.

After dispatching them, loot the corper in the corner to get a Skeptic's Spice then loot the Radiant Lifegem x2 and x2 Twilight Herb. Pull the lever and this will raise the gate blocking the misty door below. The misty door leads to another boss fight.

Boss: Belfry Gargoyles

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.

Gargoyle Hunt

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

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.

The Bastille Key is also used to open some of the closed gates in Sinner's Rise. The flooded corridor leading to the boss area has a locked cell that can be opened with this key. Loot the Fire Seed from the skeleton.

If you haven't defeated the Lost Sinner yet, you can open the two doors at the end of the two set of stairs from the boss area. Light the oil with your torch and it will illuminate the Lost Sinner's area. You can also get a Small Smooth and Silky Stone from the corpse in one of those rooms.

There's also a skeleton in the cell beside where Straid is found. Use the Bastille Key to open that cell and loot the skeleton to get a Petrified Dragon Bone and Firebomb x3

Your next destination is Huntsman Copse. To access this area, you have to have to make Licia to Majula so you can pay 2000 souls for her to move the contraption leading to this area. Licia is found in the bonfire after defeating the Old Dragonrider boss in Heide's Tower of Flame. Exhaust her dialogue to make her move to Majula.