- For tactics on her encounter, see Hellfire High Council.
Dia Darkwhisper, a champion of Void magic and an outcast of the Shadowmoon, rose quickly to power and became the left hand of Gul'dan. She is now apart of the Hellfire High Council, which serves her master as both a Highguard and a Council of War.
- Void Bolt — Dia focuses void energy at her primary target, inflicting 150000 Shadow damage.
- Void Haze — Dia's dark presence shrouds allies in a dark haze, absorbing all damage taken for as long as they stand within 25 yards of her.
- Nightmare Visage — Dia transforms into a visage of nightmares, unleashing a flurry of attacks on her primary target.
- Mark of the Necromancer — Dia marks random enemies with the sigil of the necromancer, inflicting increasing Shadow damage over time. When dispelled, this effect bounces to 2 nearby allies of the afflicted player. In Mythic difficulty, Mark of the Necromancer bounces to 3 targets, instead of 2.
- Reap — Dia reaps all marked targets, causing her mark to burn into the ground. This mark inflicts 58500 to 61500 Shadow damage to all enemies within the effect every second.
- Burden of the Necromancer — When Mark of the Necromancer is dispeled, it will detonate for 29250 to 30750 Shadow damage to all enemies.
- Wailing Horror — Dia shrouds the room in darkness, inflicting 102375 to 107625 Shadow damage to all enemies every second. Darkness amasses, causing Wailing Horrors to form in random locations and sail across the room. These horrors will inflict 102375 to 107625 Shadow damage to enemies with which they come into contact.
- Her Final Hour — Upon reaching 30% health remaining, Dia Darkwhisper is overcome by darkness, applying Mark of the Necromancer to half of all remaining foes. In her madness, she will no longer use Reap.
- Main article: Hellfire High Council#Quotes