Cornerstone is a Nightmare Unique ring, hunted from The Mountain Sire once you are at Threat 20 or higher. It is one of four ordinary drops on its list — 22.5% of the Uniques that boss gives up, about 1 in 4 — and every kill rolls the list twice. It is built on Immaculate Gravestone Band — step 6 of the Gravestone Band line, item level 80 and up.
It always rolls the same numbers: +52 Armor, +14% Stone Damage, +63 Maximum Health, +112% Stone Damage, +290 Maximum Health and +69% Power.
On top of that it carries Cornerstone — You have 25% more Armor.
It is Nightmare Gate loot.
“Everything since was built on this.”
Item text
as it reads in game
+52 Armorbase
+14% Stone Damage
+63 Maximum Health
+112% Stone DamageT9 · 45–61 · over the usual range
+290 Maximum HealthT9 · 346–490 · under the usual range
+69% PowerT9 · 31–41 · over the usual range
Cornerstone — You have 25% more Armor.
The numbers it locks in
the same on every copy
| Affix | Tier | Value | Normal range |
|---|---|---|---|
| Stone Damage prefix | T9 | +112% | 45–61 |
| Maximum Health suffix | T9 | +290 | 346–490 |
| Power prefix | T9 | +69% | 31–41 |
The part the stats don't show
what makes it worth hunting
Cornerstone
You have 25% more Armor.
1 effect: stat
Plays with
what to build around it
Found inNightmare Gate
Everything that boss drops
The Mountain Sire · 2 rolls per kill
| Unique | Built on | Kind | Weight | Share of its drops | |
|---|---|---|---|---|---|
 | The Quarry Warden's Brow | Sovereign Stonegaze Helm Head | LESSER | 90 | |
 | Cornerstone | Immaculate Gravestone Band Ring | LESSER | 90 | |
 | The Switchbacks | Exalted Longroad Boots Boots | LESSER | 90 | |
 | Rubble Rampart | Sovereign Gravewall Shield Off Hand | LESSER | 90 | |
 | Bedrock Testament | Sovereign Anchor Tower Shield Off Hand | EXCEPTIONAL | 10 | |
 | The Mountain Sire's Spine | Sovereign Atlas Zweihander Main Hand | EXCEPTIONAL | 10 | |
 | Sediment | Sovereign Stonegaze Helm Head | EXCEPTIONAL | 10 | |
 | The Landslide Clause | Immaculate Ironvow Band Ring | EXCEPTIONAL | 10 |
Other Unique rings
19 to compare
EmberheartThreat 3·
The Gardener's BandThreat 6·
Patient ZeroThreat 13·
Clutch of EyesThreat 20·CornerstoneThreat 20·
Deepfrost SignetThreat 20·
Invitation to the BanquetThreat 20·
Slagheart SignetThreat 20·
Solstice VigilThreat 20·
Static ClingThreat 20·
The Courtier's SealThreat 20·
The Dawn OffertoryThreat 20·
The Ember LedgerThreat 20·The Landslide ClauseThreat 20·
Tithe of the CourtThreat 20·
WeathervaneThreat 20·
The Sleepless EyeThreat 25·
The Jeweler's Last StoneThreat 26·
The Second SunriseThreat 26