Complex sentence: A powerful necromancer, Thulsa Doom is Kull's primary foe, and later becomes an enemy of the Celtic hero Cormac mac Art, another Howard character further expanded by Andrew J. Offutt.
Split into simpler sentences: A powerful necromancer, Thulsa Doom is Kull's primary foe. He later becomes an enemy of the Celtic hero Cormac mac Art, another Howard character further expanded by Andrew J. Offutt.