Greenwalker's Oath is a Unique Boots in Diablo IV Season 15. It comes from World drop (any difficulty, drop rate scales with Torment tier); Dedicated drop: Duriel, King of Maggots (Greater Lair Boss, Torment 1+; Boss Trophy: Shard of Agony); 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
Poison Creeper gains the Germinate Variant for free and deals [30-40%][x] bonus damage.
Affixes
600 Armor
+[1-3] to Poison Creeper (1-3)
Where it drops
World drop (any difficulty, drop rate scales with Torment tier)
Dedicated drop: Duriel, King of Maggots (Greater Lair Boss, Torment 1+; Boss Trophy: Shard of Agony)
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 Shard of Agony (Boss Trophy) rolls a Unique from this boss's pool; can roll Mythic quality with the 'Crafted' tag