During the Dark Exile, the Prime Evils were banished to the mortal realm by the Lesser Evils. In the mortal realm they caused widespread ruin and suffering. Eventually, the Archangel Tyrael intervened. He provided the mortal Horadrim Brotherhood three powerful gemstones known as Soulstones, capable of holding the vile demons' spirits. Now that humanity was equipped to combat Evil, the hunt for the Three began.
The Lord of Hatred, Mephisto, was the first of the three brothers to be caught and imprisoned within a soulstone. He was then entombed beneath the Temple of Light within the temple city of Travincal in Kurast, where the esteemed High Council of Zakarum watched over him. However, overtime, Mephisto's insidious power started corrupting both his soulstone and his human jailors. Ultimately he ordered the Zakarum priesthood to shatter his soulstone, freeing his spirit. Each of the fallen priests drove a shard of the soulstone through their left palms, with the largest shard piercing the hand of the high-priest Sankekur. In time Sankekur would become the mortal host for Mephisto's spirit.
Mephisto was later defeated within his lair, the Durance of Hate, underneath Travincal. Later on it was revealed by Izual that the Prime Evils had masterminded their own exile and had allowed themselves to be bound within the soulstones. By corrupting the stones the Prime Evils could now tap into their tremendous powers (the stones were linked to the Worldstone itself). After learning about the soulstone's corruption, Tyrael ordered the stones to be destroyed. Mephisto's soulstone was then taken to the one place where it could be destroyed, the Hellforge, where it was subsequently shattered. This act banished Mephisto's spirit back to the Black Abyss, presumably preventing him from ever manifesting in the mortal realm again.
- In Diablo II, players can obtain Mephisto's Soulstone after defeating the Lord of Hatred within the Durance of Hate in Act III. Deckard Cain then tasks the player with destroying the soulstone in a quest in Act IV. If the player did not pick up the soulstone, he/she will receive it from Deckard Cain at the start of the quest. The player must then proceed to destroy the soulstone at the Hellforge.
- It is possible to trade the item with other players online, but it has zero value if sold to an NPC vendor.