Deacons of the Deep
Maximum souls: 193,330
From the Crystal Sage bonfire, use the Ring of Favor glitch to sprint to the Cleansing Chapel bonfire. Halfway through the route, a number of Starved Hounds might chase after you. These enemies are relentless and can teleport behind you. If you want, consider casting Tears of Denial before you start the sprint, use Alluring Skulls to distract the Hounds, or cast Hidden Body. From the Cleansing Chapel bonfire, you can sprint straight to the Deacons. Some enemies in the grave yard can block your path. Use a fire weapon to clear your path as necessary. If you want, have the Torch and/or Bloodred Moss Clump ready in case you're hit with maggots, which would cause bleeding. Once you're hit with maggots, use the Torch or consume a Bloodred Moss Clump to rid yourself of maggots and remove the bleed bar.
The Deacons is a gank boss, but can easily be cheesed by means of the Dragonslayer's Greataxe+5. Equip the Flame Stoneplate Ring+2 and consume a Red Bug Pellet. Before entering the fog wall, cast Sacred Oath or use the weapon art of the Sunlight Straight Sword, and cast Deep Protection if need be. Equip Alluring Skulls and 2-hand your weapon. After entering the fog wall, throw an Alluring Skull and look for the Deacon with a glowing crimson aura to kill. Repeat for the duration of the first phase, throwing an Alluring Skull each time before you start killing the crimson-glowing Deacon. In the second phase, the head Deacon would spawn in, surrounded by a number of purple robed deacons. Stand next to the head Deacon, lock on to him, and use the weapon art of the Dragonslayer's Greataxe. If your Stamina bar is near empty or fully depleted, strafe around the head Deacon to recover some Stamina for a weapon art. Repeat until the Deacons are defeated. The following video shows the above strategy.
Deacons NG+40 Dragonslayer's Greataxe, Dark Souls III
Depending on how far you have progressed with Anri and/or Sirris' quest lines, you can summon any of the following NPCs to help you: Anri, Horace, Sirris.