This Key drops from The Countess who is located in the Tower Cellar Level 5 underneath Black Marsh. The best Characters for this task have access to Teleport, either from being a Sorceress or granted by gear. You need a set of 3x key of terror, key of hate, and key of destruction. The first step in order to face the Uber Bosses is farming the Keys required to open the red Portals.

The last of the 3 Uber Bosses that is killed drops the Hellfire Torch, choosing a random Class for its +3 to Class Skills.

This adds even more difficulty to the fight.

While fighting the Uber Bosses in Tristram they spawn monsters on top of you.

Combine these Organs to open a fourth red Portal in Harrogath, which leads to Tristram, where you face Uber Mephisto, Uber Diablo, and Uber Baal.

Fight Lilith in the Matron's Den, Uber Duriel in the Forgotten Sands, and Uber Izual in The Furnace of Pain to receive Mephisto's Brain, Diablo's Horn, and Baal's Eye.

!!MAKE SURE TO NOT PUT THE PORTALS ON TOP OF EACH OTHER!!

To fight Uber Bosses, 3 red Portals have to be opened in Harrogath by putting the Key of Terror, Key of Hate, and Key of Destruction into the Horadric Cube.Defeating this challenge rewards you with the Hellfire Torch, giving a big power boost to your Character. You are faced with regular bosses ( The Countess, The Summoner, and Nihlathak) the 3 ' Mini Ubers' ( Lilith, Uber Duriel, and Uber Izual) and the Uber versions of the Prime Evils ( Uber Mephisto, Uber Diablo, and Uber Baal). The Pandemonium Event, also known as ' Ubers' or ' Uber Tristram', is the ultimate challenge in Diablo 2 Resurrected.

Key of terror diablo 2