Irithyll of the Boreal Valley

A frozen moonlit city of Silver Knights, home of Pontiff Sulyvahn.

Suggested level: 50–60

Bosses

Pontiff Sulyvahn: A fast twin-sword duellist who summons a mirror copy of himself at half health.

Bonfires

Irithyll of the Boreal Valley
Central Irithyll
Church of Yorshka
Distant Manor
Pontiff Sulyvahn
Water Reserve

Items found here

Anri's Straight Sword: Finish Anri's questline and find it in the Darkmoon Church, or get it from Ludleth after the alternate ending of her story.
Dragonslayer's Axe: Dropped by Creighton the Wanderer when he invades in the graveyard below the Church of Yorshka (Sirris questline).
Smough's Great Hammer: In a chest in the hidden gallery up a staircase off the Silver Knight room past the sewers (Distant Manor side).
Yorshka's Spear: In a chest on a wooden platform you drop to from the rafters of the dark room below the Church of Yorshka.
Golden Ritual Spear: Dropped by a mimic across the bridge after opening the shortcut beyond Pontiff Sulyvahn's arena.
Drang Twinspears: Dropped by the two NPC attackers at the end of the large courtyard past Pontiff Sulyvahn.
Immolation Tinder: Random drop from Fire Witches around the altar below Pontiff Sulyvahn's arena.
Pontiff Knight Great Scythe: Random drop from scythe-wielding Pontiff Knights in front of Pontiff Sulyvahn's arena.
Dragonslayer Greatbow: On a platform below the shortcut ledge in the area guarded by greatbow-firing Silver Knights, before Anor Londo.
Witchtree Branch: Down an illusory staircase from the balcony with a Crystal Lizard, next to a screaming Evangelist.
Creighton's Steel Mask: Appears on the main bridge into Irithyll after killing Creighton the Wanderer during Sirris's questline.
Brass Helm: Inside the Darkmoon Church, reached from the round room by the Anor Londo elevator (behind an illusory wall unless opened).
Pontiff Knight Crown: Random drop from Pontiff Knights, several of which stand before Pontiff Sulyvahn's arena.
Fire Witch Helm: Random drop from Fire Witches around the altar below Pontiff Sulyvahn's arena.
Mirrah Chain Mail: Appears on the main bridge into Irithyll after killing Creighton the Wanderer during Sirris's questline.
Brass Armor: Inside the Darkmoon Church, reached from the round room by the Anor Londo elevator (behind an illusory wall unless opened).
Pontiff Knight Armor: Random drop from Pontiff Knights, several of which stand before Pontiff Sulyvahn's arena.
Fire Witch Armor: Random drop from Fire Witches around the altar below Pontiff Sulyvahn's arena.
Mirrah Chain Gloves: Appears on the main bridge into Irithyll after killing Creighton the Wanderer during Sirris's questline.
Brass Gauntlets: Inside the Darkmoon Church, reached from the round room by the Anor Londo elevator (behind an illusory wall unless opened).
Pontiff Knight Gauntlets: Random drop from Pontiff Knights, several of which stand before Pontiff Sulyvahn's arena.
Fire Witch Gauntlets: Random drop from Fire Witches around the altar below Pontiff Sulyvahn's arena.
Mirrah Chain Leggings: Appears on the main bridge into Irithyll after killing Creighton the Wanderer during Sirris's questline.
Brass Leggings: Inside the Darkmoon Church, reached from the round room by the Anor Londo elevator (behind an illusory wall unless opened).
Pontiff Knight Leggings: Random drop from Pontiff Knights, several of which stand before Pontiff Sulyvahn's arena.
Fire Witch Leggings: Random drop from Fire Witches around the altar below Pontiff Sulyvahn's arena.
Ring of Favor: Reward for killing the two Sulyvahn's Beasts below an illusory wall in the building at the end of the courtyard past Pontiff Sulyvahn.
Dark Stoneplate Ring: In the dark area left after leaving Pontiff Sulyvahn's arena, around a corner to the right.
Ring of the Sun's First Born: On an upper ledge of the big altar below Pontiff Sulyvahn, reached by dropping from opposite the fog gate.
Leo Ring: In a chest in the hidden gallery up a staircase off the Silver Knight room past the sewers (Distant Manor side).
Ring of the Evil Eye: Given by Anri of Astora at the Church of Yorshka during her questline.
Magic Clutch Ring: Behind an illusory wall to the right of the big altar below Pontiff Sulyvahn's gate.
Pontiff's Right Eye: Dropped by the Sulyvahn's Beast on the bridge into Irithyll.
Chloranthy Ring+1: NG+: behind the big altar below Pontiff Sulyvahn's arena.
Ring of Favor+1: NG+: by the railing near the bridge after opening the shortcut back to the cathedral past Pontiff Sulyvahn.
Covetous Gold Serpent Ring+1: NG+: below a broken railing outside the dark room under the Church of Yorshka.
Wood Grain Ring+2: NG++: in an alcove right outside the Silver Knight room past the sewers (Distant Manor side).
Chameleon: Irithyll: dropped by the statue-disguised assassin in the Church of Yorshka during Anri's quest; another copy lies in the Darkmoon Tomb.
Great Heal: Irithyll of the Boreal Valley: on a corpse in the lake area below the Church of Yorshka.
Emit Force: Given by Siegward of Catarina in Irithyll after you rescue him from the well; lost if his quest breaks.
Dorhys' Gnawing: Irithyll of the Boreal Valley: drops from the screaming Evangelist behind an illusory fence near the start.
Quiet Resolve: Anri of Astora gives it near the Church of Yorshka bonfire if you keep following their questline.
Sword of Avowal: Given by a Londor pilgrim near the Darkmoon Tomb entrance if Anri's questline reaches the wedding stage.
Excrement-covered Ashes: Irithyll: in a small dead-end alcove of the sewers below the lake.
Easterner's Ashes: Irithyll: on a lower roof of the building where Silver Knight archers shoot at you.
Soul of Pontiff Sulyvahn: Dropped by Pontiff Sulyvahn.
Undead Bone Shard: Irithyll: behind the largest gravestone, right from the Church of Yorshka down the stairs.

Walkthrough: Irithyll of the Boreal Valley

On arrival, kill the Sulyvahn's Beast for Pontiff's Right Eye. If you run past it, it turns up later in a nastier spot.
Light Central Irithyll, then use Sirris' sign mid-bridge to beat Creighton the Wanderer. At the shrine she rewards you with a blessed Mail Breaker and the Silvercat Ring.
A Homeward Bone sits just before the barrier.
Around the fountain: a Large Soul of a Nameless Soldier, a Rime-blue Moss Clump and a Soul of a Weary Warrior.
Up the stairs, on the left railing, is a Soul of a Weary Warrior.
Straight on and up two flights to the right is a Large Titanite Shard.
The next fountain has a Budding Green Blossom and a Large Soul of a Nameless Soldier.
A little further, by a tree on the left, is Rime-blue Moss Clump x2.
Near the Fire Witch is a Large Titanite Shard.
Left of the main road a Crystal Lizard drops a Twinkling Titanite.
Hit the railing right of the lizard to reveal stairs; go down and right for a Large Titanite Shard.
The Evangelist below drops Dorhys' Gnawing.
Take the Witchtree Branch, open the gate and return to the lizard spot.
Before the crossroads is a Large Soul of a Nameless Soldier.
Go right at the crossroads for a Large Titanite Shard on a body.
Go left at the crossroads; before the church, a Large Titanite Shard lies on the left.
Inside, light the Church of Yorshka bonfire and take Proof of a Concord Kept at the back.
Anri is here: exhaust her talk for the Quiet Resolve gesture and the Ring of the Evil Eye if you lack it.
Now pick a branch: route A ends her story fighting Aldrich, route B (leave the statues alone) leads to the Usurpation of Fire.
Route A: hit the statues until you find the disguised pilgrim and kill him. He drops Chameleon.
Route B: ignore the hidden pilgrim completely.
Downstairs and right is the Roster of Knights. In the graveyard, a Fading Soul lies near the cliff and another by a tree on the right.
Before the big tombstone at the end are Homeward Bone x3.
An Undead Bone Shard lies behind the grave.
If you helped Sirris and are embered, Creighton the Wanderer invades here. He drops the Dragonslayer's Axe, and his Mirrah Chain Set appears on the bridge where Sirris' sign was.
From the graveyard entrance take the stairs down and left twice for Kukri x8 and a Rusted Gold Coin.
The other way leads to a dark room with Blue Bug Pellet x2 on the ground floor.
On the rafters is a Shriving Stone; a chest on the middle level holds Yorshka's Spear.
NG+ only: step through the broken railing outside and drop to a ledge for the Covetous Gold Serpent Ring+1.
Down the stairs before the lake, the first tunnel on the right has a hidden wall with a Crystal Lizard (Twinkling Titanite).
Past the other tunnel, by the tree, is a Blood Gem.
Leap down into the lake from this spot; a Ring of Sacrifice lies where you land.
In the lake: Green Blossom x3 twice, a Large Soul of a Nameless Soldier, a single Green Blossom and the Great Heal miracle on the right side under the city entrance.
Light the Distant Manor bonfire and head back up.
Enter the sewer from the lake and collect two Dung Pie x3 piles.
In the corner opposite the stairs are the Excrement-covered Ashes.
Up those stairs Siegward of Catarina rests by a fire. Exhaust his talk for the Emit Force miracle, a Siegbräu and any gestures you missed.
The first Silver Knight in the next room drops a Large Titanite Shard and a Divine Blessing; two more up the left stairs drop Large Titanite Shard x2.
Three chests up there hold the Leo Ring, Smough's Great Hammer and a Divine Blessing.
NG++ only: the Wood Grain Ring+2 is in an alcove outside on the right.
If Yuria is hostile (cured Sigils, attacked her or killed the pilgrim) and you are embered, the Londor Pale Shade invades after the knights' room; a first kill gives the Manikin Claws.
Beat both of the Shade's invasions and the Pale Shade Set appears near Yuria's spot in Firelink Shrine.
By the stairs is a Large Soul of a Nameless Soldier; higher on a railing is a Large Titanite Shard.
Ride the lift here and open the gate as a shortcut.
In the next room take Blue Bug Pellet x2, then go down the ladder at the top for a Large Titanite Shard.
Outside is a Soul of a Weary Warrior.
Go down left of the boss fog for an Ember and open another shortcut.
Drop from the fog area onto the altar for the Ring of the Sun's First Born and a Lightning Gem.
NG+ only: the Chloranthy Ring+1 is behind the altar.
With your back to the altar, the wall on the left is fake and hides the Magic Clutch Ring.
Take the opposite exit for a Soul of a Weary Warrior at the Fire Witch spot and another above it.
Greirat asks to pillage Irithyll. Only agree if Siegward is in the sewer here or Patches still sells Siegward's armor; otherwise Greirat dies.
If Patches still has the armor, reload after sending Greirat and tell Patches where he went so he can rescue him.
Black Hand Gotthard can be summoned for Pontiff; first summon gives By My Sword.
Following Yoel and Yuria, you can summon the Londor Pale Shade; first summon gives the Duel Bow gesture.
Anri of Astora can be summoned instead of the Shade.
Defeat Pontiff Sulyvahn for the Soul of Pontiff Sulyvahn.
Route B: talk to Yuria; she says the wedding is nearly ready.
Greirat should be back from his trip.
Go right from the Pontiff bonfire for a Large Titanite Shard.
Two Crystal Lizards nearby each drop a Twinkling Titanite.
Left of the courtyard in the dark section is the Dark Stoneplate Ring.
From the top of the dark area, slip into the cathedral, open the lift to Sulyvahn's hall, then cross the bridge; a Mimic there drops the Golden Ritual Spear.
NG+ only: the Ring of Favor+1 is at the far end.
Over the bridge and around, a Crystal Lizard drops a Simple Gem.
Leave the same way and go right for a Large Titanite Shard.
In the big courtyard: a Soul of a Weary Warrior, a Large Titanite Shard and two Ember pickups.
At the end of the courtyard, one of two NPCs drops the Drang Twinspears.
In the next building, a hidden wall on the left reveals a long ladder. Kill the two Sulyvahn's Beasts below for the Ring of Favor.
Join the Aldrich Faithful with Archdeacon McDonnell and grab Human Dregs and a Deep Gem by the Water Reserve bonfire.
Up the stairs of that building, a body in an outer corner has a Titanite Scale.
Beside the right tower by the archers is a Large Titanite Shard.
While climbing past the Silver Knight archers, drop to a roof below for the Easterner's Ashes.
Short of the lift corridor, descend into the lower tower for a Large Titanite Shard, then unlock the door in the following tower.
On the way back, the Dragonslayer Greatbow and Dragonslayer Greatarrow x5 sit on a lower platform.
Route B: before the lift lever, a path leads down to the pilgrim, who hands you the Sword of Avowal.
Route B: take the Brass Set on the way down and perform the Rite of Avowal on Anri's body for 3 more Dark Sigils (8 in total).
Take the Reversal Ring right of the altar. The pilgrim later lies dead with Chameleon on his body.
Route B: reload and take Anri's Straight Sword from where she lay.
Route A: a hidden wall replaces the path to the altar; the Brass Set and Reversal Ring are in the same spots.
An Ember lies before the lift.