Mjolnic Ryng is a Unique Ring in Diablo IV Season 15. It comes from World drop (any difficulty, drop rate scales with Torment tier); Dedicated drop: Bartuc, Lord of Chaos (Infernal Hordes, 666 Burning Aether; Boss Trophy: Chaotic Essence); 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
While Cataclysm is active, you gain unlimited Spirit and deal [45-60%][x] increased damage.
Affixes
+111 All Resist
+[1-2] to Nature Magic Skills (1-2)
Where it drops
World drop (any difficulty, drop rate scales with Torment tier)
Dedicated drop: Bartuc, Lord of Chaos (Infernal Hordes, 666 Burning Aether; Boss Trophy: Chaotic Essence)
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 Chaotic Essence (Boss Trophy) rolls a Unique from this boss's pool; can roll Mythic quality with the 'Crafted' tag