You will need 3x Artificer’s Stone to open a portal to the Pit. In Diablo 4, this content becomes available once your character is strong enough to take on high-level enemies and handle tight ...

Diablo 4's Season of Loot Reborn has greatly expanded ... The Pit is unlocked upon completing the "Pit of the Artificer" quest. It should unlock after you reach World Tier 4: Nightmare difficulty.