Fleshrender is a Unique One-Handed Mace in Diablo IV Season 15. It drops from Harbinger of Hatred.
Unique power
When Tornadoes expire, they instead seek back toward you. Tornadoes deal [100-135%][x] bonus damage to enemies hit. (Patch 3.2.1: bonus now applies to ALL Tornadoes instead of only returning ones; increased from 40-50%[x] to 100-135%[x].)
Affixes
1,727 DPS; [1,256-1,884] Damage per Hit; 1.10 Attacks per Second
+[1-3] to Tornado (1-3)
Where it drops
World drop (any difficulty, drop rate scales with Torment tier)
Dedicated drop: Harbinger of Hatred (Greater Lair Boss, Torment 1+; Boss Trophy: Abhorrent Heart)
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 Abhorrent Heart (Boss Trophy) rolls a Unique from this boss's pool; can roll Mythic quality with the 'Crafted' tag