According to 1 Chronicles 10, which king died for his unfaithfulness, including consulting a medium?

Answer: Saul

Saul did not keep the LORD's word, consulted a medium and failed to inquire of the LORD, so the kingdom was turned over to David.

“So Saul died for his unfaithfulness to the LORD, because he did not keep the word of the LORD and even consulted a medium for guidance, and he failed to inquire of the LORD. So the LORD put him to death and turned the kingdom over to David son of Jesse.”— 1 Chronicles 10:13-14 (BSB)