Lair Bosses
Bosses like Grigoire, Varshan, or Diablo 4 Items Duriel can drop Runes (especially Legendary ones).
Great option when targeting Uber Unique or Summoning Mats anyway.
Helltide Chests
Good for general loot, with occasional Rune drops.
RNG-heavy but worth doing when Helltide is active.
Tree of Whispers Caches
Whisper Caches often contain Runes.
Useful for passive farming while clearing Bounties.
Augment Caches
Can be purchased with reputation in the Mercenary's Den.
Requires Tier 8 rapport with Aldkin, making it more late-game focused.
Why Runes Are Non-Negotiable in the Endgame
Crafting Mythic gear - the pinnacle of item progression in Diablo 4 - demands:
2 Resplendent Sparks
6 Magic Runes
6 Rare Runes
6 Legendary Runes
These materials are challenging to accumulate, especially Legendary Runes, which are gated behind high-difficulty activities and advanced tribute rewards. Because of this, Undercity farming becomes the cornerstone of high-end character optimization.
Without Runes, players are essentially locked out of:
Top-tier Mythic item crafting.
Max-performance builds in competitive content.
Access to the strongest passive and active buffs.
Final Thoughts: Why This Route Reigns Supreme
In a season loaded with new mechanics and challenges, efficiency is everything - and Kurast Undercity with Tribute of Harmony delivers just that. It rewards players who are already investing time in Nightmare Dungeons by giving them a way to convert that effort into powerful crafting materials that matter.
Other methods can supplement Rune farming, but none match the guaranteed consistency, scalability, and buy duriel mats direct synergy with build progression that this route offers.
If you're serious about pushing builds to their limits in Diablo 4 Season 9, this is one farming strategy you cannot afford to ignore.