Dirge of Airidah is a Unique Ring in Diablo IV Season 15. It comes from World drop (any difficulty, drop rate scales with Torment tier); Dedicated drop: Astaroth, the Charred Duke (Escalating Nightmare Dungeon boss; Boss Trophy: Ash of the Charred Duke); Horadric Cube: Item Transmutation (Upgrade to Unique) - Common item of the same slot + 1 Enhanced Primordial Dust + 10 Primordial Dust (random Unique of that slot).
Unique power
Storm Skills that you Cast grant 1 Spirit and deal [25-35%][x] bonus damage. These bonuses are doubled when damaging a Vulnerable, Immobilized or Slowed enemy.
Affixes
+111 All Resist
+[4-14]% Vulnerable Damage (4-14%)
Where it drops
World drop (any difficulty, drop rate scales with Torment tier)
Dedicated drop: Astaroth, the Charred Duke (Escalating Nightmare Dungeon boss; Boss Trophy: Ash of the Charred Duke)
Horadric Cube: Item Transmutation (Upgrade to Unique) - Common item of the same slot + 1 Enhanced Primordial Dust + 10 Primordial Dust (random Unique of that slot)
Horadric Cube: Item Transmutation (Amalgamation) - 5x Ash of the Charred Duke (Boss Trophy) rolls a Unique from this boss's pool; can roll Mythic quality with the 'Crafted' tag