Act 2 - Tor Gul, the Defiler - exploitable bug

Hi, I am playing Monk (30th level), and during my endeavours in Act 2, I found an exploitable bug when I approached the Tor Gul, the Defiler. When you come to the area, the monologue of "bad guy" starts (How predictable you are...), and if you leave the area and stay in the entrance, the game will lock you up outside the "arena". Nevertheless, you can still hit the boss with a range attack (I have used Storm Wave) without him even starting to fight. You can kill him like this, earn the rewards and continue normally. I have tried twice with the same result. I didn't try to find the exploit, but I was too scared to be near the boss :-) Thank you for this wonderful game anyway!

https://photos.app.goo.gl/8UymnvjCFVnbe6Lx8