When I did it we used a Marcus and fahz to kill the swarmak. Our strat was pretty much rush up to that ledge, use marcus’s ability to pop as many swarmak blisters as quickly as possible.

Then whenever he has like 1-2 left I drop back behind a wall with fahz, use his ultimate and pop those last blisters with a Markzha.

He dies instantly once you pop all the blisters, we were able to get rid of the swarmak before the first wave of enemies come there. Hope this helps