There are still some areas to see. Incubus's big move is defined as follows: Magic Teng narrows the vision of all enemy heroes and removes the friendly vision of enemy heroes for 4 seconds. After the Magic Teng is activated, it can rush to any enemy hero nearby and cause 150/250/350 physical damage to the target.
When the incus is enlarged, all enemy heroes can only see a small area next to them, including heroes, and nothing can be seen except this area.