The Season of Blood stream today revealed the farming methods for Uniques! Also, these bosses will be added to Eternal at the same time.
There will be 5 bosses in Season 2 that will have their own drop tables, with specific Unique items on them. We have the returning Varshan from Season, the Season 2 endboss, Lord Zir, and 3 new bosses, Galvanic Saint, the Beast in the Ice and Duriel, King of Maggots:
These bosses will be summoned using specific materials. For example, the Saint will require Helltide mats. Lord Zir will require World Boss and Legion event mats. Varshan will require Tree of Whispers bounty mats (since his lair is beneath the tree). And finally, Duriel will require materials from the other bosses in World Tier 4. He will also have an increased chance of dropping Uber Uniques! Said Uber Uniques will always drop at the new item power level cap of 920.
And as a final note, the materials needed to summon these bosses will be tradable between players.
Update: and here’s the official post on the matter, from the Season 2 preview:
Conquer Brutish Endgame Bosses
Reinforcements from the darkest depths of the Burning Hells take hold of Sanctuary, ushering in a new era of death and wanton destruction. This batch of Uber difficulty Endgame bosses are not for the faint of heart, but the chance to receive Unique items and Cosmetic items await those who muster the courage to stand against them. Each boss has a variety of Unique items they can drop, with some of those being exclusive to only that boss. The same goes for the special Cosmetic items they can potentially drop.
You can test your hand at slaying these unsightly abominations in the Eternal or Seasonal Realms starting in World Tier III, with even more intense encounters awaiting you in World Tier IV. These foes will only grant you an audience on their terms.
Below is a list of the bosses and the requirements to encounter them.
Grigoire, The Galvanic Saint (World Tier III and IV): You must gather enough Living Steel from the Tortured Offering in Helltide. In addition to Unique items that can only drop from Grigoire, you also have a chance to receive the Demonbinder Mount Armor Cosmetic.
Echo of Varshan (World Tier III and IV): Defeat Grotesque Debtors during Whispers of the Dead for a chance to receive parts of Varshan’s body. The Tree of Whispers collections—gained from turning in Grim Favors—guarantees a part of Varshan’s body. Once you have enough parts, including a Malignant Heart if you’re playing on World Tier IV, you can summon Varshan. The Flesh-Weld Rod Trophy has a chance to drop from this boss in addition to Unique items that can only drop from Varshan.
The Beast in the Ice (World Tier IV): Gather Distilled Fear while completing Tier 30 or higher Nightmare Dungeons. After you have enough, visit the Occultist and craft the Glacial Fissure Nightmare Sigil, activate it, then you can fight The Beast in the Ice. The Skull Torch and Fell Steed Mount Trophies can potentially drop from this boss, in addition to Unique items exclusive to it.
Dark Master (World Tier IV): Defeat a World Boss on World Tier IV or complete a Legion Event. From these activities you’ll acquire Exquisite Blood. Once you have enough, you’ll be able to summon the Dark Master. The Diadem of the Ancient Helm Cosmetic can potentially drop from this boss, in addition to Unique items exclusive to it.
Echo of Duriel (World Tier IV): Defeat both Grigoire, The Galvanic Saint and Varshan in World Tier IV to collect Mucus-Slick Eggs and Shards of Agony. Once you have enough, you’ll be able to summon the Lord of Pain, Duriel! Out of this group of Bosses, Duriel is the only one who has a chance to drop Uber Unique items. The smoldering Brimstone Mount can also potentially drop from this boss.
Keep in mind that:
You’ll need to meet the summoning conditions of a boss each time you want to fight it, so hold on to any additional summoning materials that you might acquire during your travels.
Developer’s Note: We have received feedback that there is a lack of variety in the Endgame experiences offered and that there are not enough opportunities to farm Unique and Uber Unique items. This group of Endgame bosses were created to pose a challenge to high-level players while allowing them to farm sought-after items in a fun and intense way.
These demonic barons of torment await the opportunity to grind you into dust—defy their expectations!