Blood Wake is a Unique Boots in Diablo IV Season 15. It drops from Harbinger of Hatred.
Unique power
Blood Mist casts Corpse Explosion on surrounding Corpses. When Blood Mist detonates a Corpse, its Cooldown is reduced by 1 second and you gain [50 - 60]%[+] increased Movement Speed for 3 seconds.
Affixes
+1-3 to Blood Mist
Where it drops
Harbinger of Hatred (Lord of Hatred Lair Boss) per one guide
Random world drop / any Lair Boss (one guide: 'drops at any Difficulty Tier, increased drop rate per Torment tier'); 3.2.1: all Uniques drop from level 1 in any Difficulty; targetable via Horadric Cube reroll