Who accompanies Harry to Slughorn's Christmas party?

Luna Lovegood

Who did King Ahasuerus divorce before marrying Esther? Where can you find the Ruins of Machu Picchu? What organization was Karli Morgenthau leading in 'The Falcon and the Winter Soldier'? What is the name of the substance Red Skull sought as powerful as the Infinity Stones in Marvel Comics? What term describes the bending of light as it passes through different mediums?