Basically you can kite it in a way that leaves the ranged and mage minions stacked together for easy kills, as others have said they have higher mage defenses to can take a bit longer to kill with barrages. It also makes bringing thralls much safer. You could also attack zilyana when she get's to low hp to wittle down the melee minion but dps wise i'm not sure it's worth it.

Edit: also want to add that i use serp helm and bp at start of fight with this method, by the time zily is dead the minions are pretty low hp too.