Chasm of the Abyss

A dark pit of Humanity Phantoms below the township. Manus, Father of the Abyss, waits at its bottom.

Bosses

Manus, Father of the Abyss: Keep the Silver Pendant ready for his dark magic rain. Sif can be summoned if you saved the pup.

Cleansing Greatshield (Artorias of the Abyss): Reward for rescuing young Sif in the Chasm of the Abyss.
Dark Bead (Artorias of the Abyss): On a corpse in the Chasm of the Abyss, behind one of the Oolacile Sorcerers.
Black Flame (Artorias of the Abyss): Found on a corpse in the Chasm of the Abyss.
Soul of Manus (Artorias of the Abyss): Dropped by Manus, Father of the Abyss.

Keep your light source out. On the way down are a Crystal Lizard and a pack of Bloatheads; the Dark Bead sorcery is the prize.
An illusory floor on the left leads to a ghostly figure; follow it to an elevator that links back to Royal Wood.
Behind a hidden wall lower down, the young Sif is surrounded by Humanity Phantoms. Rescue him and pick up the Cleansing Greatshield.
Further down on the left, wipe out the Humanity Phantoms guarding the Black Flame pyromancy.
Back up the slope, a Bloathead Sorcerer guards Twin Humanities.
A big crowd of Humanity Phantoms stands over a drop; clear them and jump down for the Help me! Carving.
Descend once more and walk to the stone pillar for the White Titanite Slab. Equip the Silver Pendant before the boss.
Defeat Manus, Father of the Abyss.
If you saved the young Sif, his summon sign is inside the boss arena.
Once the Chasm of the Abyss bonfire appears, warp over to Oolacile Sanctuary; Elizabeth gives you three Elizabeth's Mushrooms.
Warp back to Firelink Shrine.