Will of Stone is a Unique Helm in Diablo IV Season 15. It drops from Grigoire, the Galvanic Saint.
Unique power
Earth Spike is now launched as a projectile. Upon impact, the projectile deals [225-300] damage to the target and summons [2-4] additional Earth Spikes.
Affixes
1,200 Armor
+[1-3] to Basic Earth Spike Skills (1-3)
Where it drops
World drop (any difficulty, drop rate scales with Torment tier)
Dedicated drop: Grigoire, The Galvanic Saint (Lair Boss, Torment 1+; Boss Trophy: Living Steel)
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 Living Steel (Boss Trophy) rolls a Unique from this boss's pool; can roll Mythic quality with the 'Crafted' tag