Complex sentence: Philomelus was using the temple's treasures at Delphi to support the mercenaries until he was defeated at the Neon by Boetia in 354 BC and committed suicide.
Split into simpler sentences: Philomelus was using the temple treasures at Delphi to support the mercenary's. However Philomelus was defeated at the Neon by Boetia in 354 BC and committed suicide.