Season 15 brings a new Seasonal Questline that takes us through memories of major events and battles from earlier games in the Diablo franchise.
Deckard Cain returns to guide us through these strange events, which eventually lead to encounters with Diablo, Baal, and Mephisto within Waking Nightmares.
Completing the questline rewards you with the three Splinters of Evil and eventually unlocks the Prime Evil Powers that make up Season 15’s main progression system.
Season 15 Story
Season of Hell’s Legacy celebrates Diablo’s history by bringing back characters, enemies, and locations from previous games through memories known as Waking Nightmares.
The story begins when Deckard Cain unexpectedly appears alongside several Dark Wanderers whose memories remain connected to the Prime Evils that once tormented them.
You will need to enter their Waking Nightmares, defeat the Prime Evil echoes found within, and recover the three Splinters of Evil they leave behind.
These events take you through recreated locations from the original Diablo and Diablo II before eventually allowing you to wield some of the Prime Evils’ power.
Season of Hell’s Legacy (Season 15) Questline
There are five main quests that make up the Season of Hell’s Legacy storyline, beginning in Tarsarak before eventually taking you across several regions of Sanctuary.
Refuge From The Memories (Quest 1)
Refuge From The Memories begins in Tarsarak, where you need to enter Kuhuthi’s Tavern and investigate a mysterious cloaked stranger found inside.
The encounter quickly turns violent as demons appear throughout the tavern, requiring you to defeat them before an unexpected Deckard Cain arrives on the scene.
Speak with Cain after the fighting ends, and he will ask you to meet him at the Imperial Library to continue investigating what is happening.
The Horadrim’s Fate (Quest 2)
Meet Deckard Cain at the Imperial Library to begin searching for Tal Rasha, who can be found within the Fractured Peaks and must initially be defeated.
Speaking with Tal Rasha afterward opens the Diablo II – Worldstone Keep Waking Nightmare, taking you through Arreat Summit and eventually into the Worldstone Keep.
Defeat the Ancients along the way before pursuing the Echo of Baal through the keep, where defeating him allows you to obtain the Splinter of Destruction.
The Burning Shepherd (Quest 3)
Return to Cain before traveling to Hawezar in search of Sankekur, who must be defeated before his Diablo II – Durance of Hate Waking Nightmare becomes accessible.
Within Travincal, you will need to collect the four components of Khalim’s Will before using them to unlock the entrance leading into the Durance of Hate.
Continue to Level 3 and defeat the Echo of Mephisto, then speak with Sankekur and collect the Splinter of Hatred that he leaves behind.
The Brother’s Keeper (Quest 4)
The Brother’s Keeper sends you to the Strand in Scosglen, where you must find and defeat Aidan before entering his Diablo – The Labyrinth Waking Nightmare.
Fight your way through the Labyrinth until you encounter Diablo, who becomes invulnerable between phases until you destroy the Portals of Darkness that appear.
Defeat the Echo of Diablo and speak with Aidan afterward, allowing you to collect the Splinter of Terror and complete your collection of three Splinters.
Legacy of Hope (Quest 5)
Return to the Imperial Library with the Splinter of Terror and speak with Deckard Cain, then place the final Splinter alongside the others on the table.
After another conversation with Cain, you will be allowed to choose one of the three Splinters and begin bearing the power of its associated Prime Evil.
Making your selection completes Legacy of Hope, finishes the introductory Seasonal Questline, and unlocks the Prime Evil Powers system for further Season 15 progression.
Season 15 Questline Rewards
Completing quests throughout the Season of Hell’s Legacy storyline provides XP and Gold while gradually introducing you to Waking Nightmares and other seasonal mechanics.
Progressing through the three major Waking Nightmares allows you to recover the Splinters of Destruction, Hatred, and Terror from Baal, Mephisto, and Diablo respectively.
Finishing Legacy of Hope allows you to choose a Splinter to bear, granting access to its associated Iconic Power and the larger Prime Evil progression system.
From there, you can build reputation through activities associated with your chosen Splinter and unlock additional modifiers and upgrades through War Plans.
Verdict
The Season 15 Questline serves as both an introduction to Hell’s Legacy and a trip through memorable locations and encounters from Diablo’s earlier games.
Each Waking Nightmare moves the storyline forward while gradually providing the three Splinters needed to unlock the season’s Prime Evil Powers and progression.
Once Legacy of Hope is complete, the main storyline may be finished, but Waking Nightmares, Splinter reputation, and War Plans provide plenty more to pursue.
