Unveiling Diablo 4's Rarest Unique Items and How to Obtain Them
Lead class designer Adam Jackson clarified that the six rarest unique items in Diablo 4 - Doombringer, The Grandfather, Andariel's Visage, Harlequin's Crest, Melted Heart of Selig, and the Ring of Starless Skies - always drop at 820 Item Power from enemies level 85+, and are "realllly rare!" blaming it on the game's RNG system.