Vastiri Outskirts Boss Defeated Ambush

After defeating the boss in the Vastiri Outskirts I was immediately ambushed by 20+ monsters. I could not dodge or begin to fight my way out of this as I was completely surrounded within a second or two.

Is this meant to be certain death? If not, maybe it should be tuned down a little.

I was playing a caster using Contagion and Essence Drain and I don't see a way for me to have dealt with this ambush.