Complex sentence: Sivana is a short, bald, self-described mad scientist with a penchant for developing unusual technologies, and who often plots to do away with Captain Marvel and his Marvel Family, but is often thwarted in his plans.
Split into simpler sentences: Sivana is a short, bald, self-described mad scientist with a penchant for developing unusual technologies. He often plots to do away with Captain Marvel and his Marvel Family, but is usually thwarted in his plans.