Possible Clues:

• Spirits initially not seen — they may be here
• Section broken off sunglasses? Hell!
• Destination in Hercules' 12th labor
• Underworld king
• Underworld ruler
• Ruler of a mythological underworld
• Titular Greek god of an Anais Mitchell musical
• Was in possession of drugs for underworld
• Realm surrounded by the Styx
• Underworld spooks beheaded