This question already has an answer here:
RAW, is there anything that explicitly states what happens to a creature (either PC or monster) when a weight that exceeds their carry capacity is suddenly dropped on them?
EDIT: The intent is to find out the mechanics, if any exist, of what would happen if a Goliath Barbearian PC unceremoniously dropped, say, a 1000 lb. iron ball on a wolf. How would damage and other things be handled? If existing mechanics can't fully describe this situation, how would you handle it at your table?