Carrion Swarm

Carrion Swarm is a Demonology warlock ability, available at level 47.

Inspiration
Carrion Swarm was one of spells available to the Dread Lord hero unit back in WarCraft III as well as such lore characters as Mal'Ganis, Tichondrius, Anetheron, Dalvengyr and Detheroc. Mal'Ganis and Varimatras retained this ability in WoW. Any of these versions didn't have knock back, though.