Fields of Crimson is a Unique Two-Handed Sword in Diablo IV Season 15. It drops from Lord Zir.
Unique power
Rupture's rip deals [38 - 50]% of the total Bleeding damage on an enemy instantly, removing all Bleeding damage from them.
Affixes
Weapon Damage
+Ranks to Rupture (1 - 3)
Where it drops
Lord Zir (Lair Boss hoard - targeted drop)
Any Lair Boss general unique pool / world drop at Torment (chance rises per Torment tier)
Horadric Cube: Item Transmutation - Upgrade to Unique (Common base of same type + 1 Enhanced Primordial Dust + 10 Primordial Dust) rolls a random unique of that item category