Worldstone Keep

The Worldstone Keep Level 3
Act	Act V
Quests	Eve of Destruction
Monsters	Death Lord, ; Rancid Defiler, ; Demon Sprite ; Spawn: ; Anguish Worm
Uniques on Normal	Death Lord, ; Fetid Defiler, ; Stygian Fury ; (Uniques are disabled on Normal)
Monsters - Nightmare,Hell	Death Lord, ; Rancid Defiler, ; Demon Sprite, ; Stygian Fury, ; Hell Tempress, ; Blood Boss ; Minions: ; Fire Boar ; Spawn: ; Anguish Worm
Guest Monsters	Storm Caster, ; Oblivion Knight, ; Soul Killer Blowdart, ; Horror Mage L, ; Specter ; Minions: ; Doom Knight
Uniques and Champions Quantity	2-3 (Nightmare) ; 6-8 (Hell)
Adjacent Zones	Worldstone Keep Level 2, Throne of Destruction
Area Level Normal	42
Area Level Nightmare	66
Area Level Hell	85
Waypoint	No

The Worldstone Keep Level 2
Act	Act V
Quests	Eve of Destruction
Monsters	Frenzied Ice Spawn, ; Greater Hell Spawn
Uniques on Normal	Greater Hell Spawn, ; Hell Lord ; (Uniques are disabled on Normal)
Monsters - Nightmare,Hell	Frenzied Ice Spawn
Guest Monsters	Greater Hell Spawn, ; Soul Killer, ; Fiend, ; Serpent Magus, ; Cadaver, ; Horror Mage P, ; Horadrim Ancient, ; Steel Scarab, ; Black Soul
Uniques and Champions Quantity	2-3 (Nightmare) ; 6-8 (Hell)
Adjacent Zones	Worldstone Keep Level 1, Worldstone Keep Level 3
Area Level Normal	40
Area Level Nightmare	65
Area Level Hell	85
Waypoint	Yes

The Worldstone Keep Level 1
Act	Act V
Quests	Eve of Destruction
Monsters	Defiled Warrior, ; Vile Witch, ; Fetid Defiler ; Spawn: ; Menace Worm
Uniques on Normal	Vile Witch, ; Wretched Defiler, ; Blood Lord ; (Uniques are disabled on Normal)
Monsters - Nightmare,Hell	Fetid Defiler, ; Death Lord ; Spawn: ; Menace Worm
Guest Monsters	Unholy Corpse, ; Vile Witch, ; Invader, ; Black Lancer, ; Flesh Spawner, ; Hierophant, ; Ghoul Lord, ; Soul Killer Shaman ; Minions: ; Zealot, ; Soul Killer, ; Soul Killer Blowdart ; Spawn: ; Flesh Beast
Uniques and Champions Quantity	2-3 (Nightmare) ; 6-8 (Hell)
Adjacent Zones	Arreat Summit, Worldstone Keep Level 2
Area Level Normal	39
Area Level Nightmare	65
Area Level Hell	85
Waypoint	No

The Worldstone Keep is the last building, protected by three Ancients, where Baal is. The entrance is sealed until those Ancients are defeated.

The most fearsome Oblivion Knights can be found there at Nightmare Difficulty and Hell Difficulty.

It is also one of the area level 85 zones on Hell added in patch 1.10, meaning the monsters there have a chance of dropping high level items compared to other places - however, due to the Willowisps and Oblivion Knights it might not be the easiest place to do Magic Find runs.