Many fallen masks appear in a specific encounter in Sliske's Endgame. They fall from the ceiling, one at a time, during an encounter with Zamorak alone, after his entourage has been removed from the maze.
The masks cannot be picked up, but if interacted with (once Zamorak leaves) they each say a single word. In the order that they dropped, this is the sentence "I Love You For More Than Your Soul".