Reikenor

One of the most trusted Nighthaunt lieutenants, Reikenor the Grimhailer was once a sorcerer-king in Hysh. Because Hyshians are known for trying to perform monumental tasks involving lots of hubris, he decided to try and unbend the very workings of death itself. You can imagine how Nagash took this. In the afterlife, Reikenor hunts not for the secrets of mortality, but for those that were once like him; petty mages, those that unbind necromantic rituals, and especially Necromancers that don't serve Nagash.

He swoops down from above on his winged Nightmare, Kyllaron, wielding a scythe and steals their souls Grim Reaper-style. These souls are then used for his own unique spell called the Wraithstorm, which involves a cyclone of these souls being let out to attack their former comrades. All across his armor and his steed's are candles that correspond to soul energy. By snuffing out a candle, he can harm someone else to give his spells a minor power boost, or draw off some of his own essence - harming himself slightly for a major power boost.

In Broken Realms: Reikenor he got his own subfaction, which buffs up Chainrasps and Glaivewraith Stalkers.