Killing Boss without entering arena

Bug report reference number 1.196.343.936

I was able to kill a boss on the mire map without entering the boss arena.
I am using the Storm wave skill and was able to just to walk against the arena entry wall and hit the boss through the wall.

Not sure yet if you can also do that on other maps as I have noticed that the boss bar appeared when approaching edges of the mire map and assumably activating the boss fight with that, which allowed me to already hit the boss.

However this would easily be abuseable in group play.

Will try to replicate this on other maps to provide further information.

I have tested this now also on the Forge map, was able to activate the boss, quit to character selection, rejoin the map and do the same as on Mire.
Just walk up to the arena entrance and start swinging, being able to hit the boss with enough aoe on the storm wave skill. Not sure if you can also do so with other skills that have enough aoe.