Fighting cruelly in the cage. Octagonal cage refers to the cage around the competition field. Because it has eight corners, it is often used as a fighting field, also known as cage fighting. The mixed fighting cage used in the World Top Professional Mixed Fighting Competition (UFC ultimate fighting championship) is called octagonal cage, which means that two people or a group of people agree to fight or fight at a certain time and place, so the agreed octagonal cage is to fight or fight in the octagonal cage.