Summoning Duriel using Shards of Agony requires precise preparation and execution in Diablo 4's endgame, turning routine farming into high-reward boss runs.
Gather Required Materials
Stock up on two Mucus-Slick Eggs from Echo of Varshan in the Malignant Burrow and two Shards of Agony from Grigoire in the Hall of the Penitent, both accessible in Torment difficulties. Farm Living Steel from Helltide Tortured Gifts to summon Grigoire repeatedly, and use Whispers of the Dead caches for Varshan's body parts, prioritizing group play to multiply summons per material set. In Season 8 and later, summoning Duriel himself is free at the Gaping Crevasse altar in southern Kehjistan, but three Shards unlock his post-fight treasure hoard for Uber Unique chances.
Optimal Party Setup
Assemble a four-player group with complementary roles: designate one summoner per rotation in alphabetical order to maximize material efficiency, including a high-damage carry like a Barbarian for quick clears. Equip poison and physical resistance elixirs or gems, plus crowd control breaks, as Duriel's attacks ramp up over time with poison pools and claw combos. Boost survivability by stacking armor potions and positioning behind the boss to dodge frontal stuns and ground stabs.
Fight Execution Tips
Enter the Gaping Crevasse directly via map waypoint, interact with the Pestilent Altar, and focus initial adds emerging from ground holes before Duriel spawns fully. Fill his Stagger Bar during blue phases for free damage windows, circling constantly to avoid poison projectiles and pools while unloading DPS from the rear. If wiped, walk back to the boss room without resetting the dungeon to conserve materials for retries.
Maximize Efficiency
Rotate Helltide-Grigoire-Varshan loops during peak hours for faster cinder and heart gains, supplementing with World Bosses or Grotesque Debtors for extras. Sell carries in trade chat to fund infinite runs, and track Helltide timers with community maps for Living Steel bursts, aiming for level 90+ gear to handle Torment scaling. This approach yields consistent Uber drops while minimizing grind time.