The Basilisk is a Unique Staff in Diablo IV Season 15. It comes from 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).
Unique power
Petrified enemies have a [80-100%][+] increased chance to be Critically Struck. Additionally, Earth Skills Petrify Healthy enemies for 3 seconds.
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