Act 2 Final Boss fight bug

Hi, i have this bug recently.

https://gyazo.com/ff9aeb173690c98e503896462844b37e
https://gyazo.com/94c366e62fb18a07722b6d8f04e6cd15

1. I enter to arena of boss and when the animation start i walk out of the arena
2. wait outside the arena.

Then the fight start, the dialogues of boss attacks appear in the chat and the boss recive 4 damage per second of the npc in the fight, im to lazy to wait until the dps change the phase of boss, but i wait up to 4000 of damage to life and the bug continues.

Cheers :)