When Cadmus killed a dragon guarding a spring sacred to this deity, he had to work for him for eight years, though Cadmus did get to marry this god's daughter Harmonia.
One offspring of this deity was the murderous Kyknos, who was building a temple from the bones of his victims before being killed by Heracles. In Sparta, youths would sacrifice puppies to this god, and a statue of him in chains stood just east of Sparta. When Cadmus killed a dragon guarding a spring sacred to this deity, he had to work for him for eight years, though Cadmus did get to marry this god's daughter Harmonia. His sister was the personification of discord, Eris, and his sons were Phobos and Deimos. For 10 points, name this Greek war god.
One offspring of this deity was the murderous Kyknos, who was building a temple from the bones of his victims before being killed by Heracles.
{Ares} (do NOT accept “Mars”)