Book of Diablo 4 Items the Dead Sacrifices

This is a no-minion build, so sacrifices are crucial:

Reapers (Skeletons) - Sacrifice for increased Shadow Damage.
Cold Mages - Sacrifice for +Vulnerable Damage.
Iron Golem - Sacrifice for +Critical Strike Damage.

Horadric Spells & Jewels

Best Combo:

Catalyst: Astral Pillar - A taunting totem that deals AoE Shadow Damage.
Infusion: Nebulous Extract - Converts Pillar damage into Shadow and adds Shadowblight procs.

Arcana:

Bloody Charm - Increased DoT.
Tranquil Stone - Adds Unstoppable.
Fractured Core - Nullifies Damage Resistance Auras.

Recommended Horadric Jewels:

Scornful Light - Increases Shadow Damage.
Elemental Brand - Boosts application rate of Shadow procs.
Cursed Brand - (Optional) Boosts Cursed enemies' debuffs.

Best Mercenary for Shadowblight Necromancer

Primary: Raheir
Skills: Ground Slam, Raheir's Aegis, Bastion, Inspiration; Offers defensive boons and crowd control.
Support: Aldkin
Skills: Flame Surge, Blight; Blight synergizes directly with diablo 4 duriel mats our DoT strategy.