Mephisto's Brain

"The Lord of Hatred left this gelatinous relic behind. Many think hatred stirs in the heart, but it begins in the mind, with thoughts and stories whispered into our ears, like worms that wriggle and gnaw their way inward and leave us infested. Mephisto's Brain reminds us that we are all vulnerable to the corrupting influence of hatred, even those who believe they are engaged in righteous work."

- Lorath Nahr^(src)

Mephisto's Brain (a.k.a. the Brain of Mephisto) is a demonic artifact left behind by Mephisto.

In-game[]

Mephisto's Brain appears in Diablo II. It is an item needed in the Pandemonium Event. It is one of the three major keys represented by body parts of the Prime Evils, the other two being Diablo's Horn and Baal's Eye.

Putting the Brain along with the Horn and the Eye in the Horadric Cube in Harrogath on Hell difficulty opens a portal leading you to Uber Tristram where the ultimate challenge awaits...

Pandemonium Event

Locations — Forgotten Sands • Furnace of Pain • Matron's Den • Über Tristram
Bosses
Keywardens — The Countess • Summoner • Nihlathak
Sub-bosses — Über Duriel • Über Izual • Lilith
Über Tristram bosses — Über Baal • Pandemonium Diablo • Über Mephisto
Items
Keys — Key of Hate • Key of Terror • Key of Destruction
Organs — Mephisto's Brain • Diablo's Horn • Baal's Eye
Rewards — Hellfire Torch • Standard of Heroes