Fighting Fire with Fire
The Blood God, Khorne is the power of chaos in its aspect of mindless and absolute violence, destroying everything and everyone within reach, slaying both friend and foe alike.
Khorne hates magic. His followers are all warriors. Khorne is opposed to the use of any form of magic, and does not grant spells to his followers under any circumstances. His prohibition against magic does not extend to magical weapons, which aid his followers in doing his work.
From Realm of Chaos: Slaves to Darkness