Possible Clues:

• Largest plutoid in the solar system
• Dwarf planet roughly the size of Pluto
• Dwarf planet named for a goddess of discord
• Judgment of Paris instigator
• Dwarf planet once known as Xena
• Dwarf planet beyond Neptune
• Greek counterpart of Discordia
• Most massive dwarf planet in the solar system
• Goddess of strife intervening in 90-Across
• Harmonia's opposite in Greek myth