Mephisto, the Lord of Hatred

The evil of Mephisto, Lord of Hatred, was so pervasive that even after he had been defeated and entombed in a soulstone, his demonic essence oozed upwards into Travincal and corrupted the Zakarum priests. Though he fell to the same heroes who killed his brothers, I fear for us should he ever return. -- Deckard Cain