What teams are you using?
I was using Mang / Marilith / Algorak the Slayer / Tai-Pan with Meteor Banner and Mech Class (for the xp)
I had purchased Tier5, so Algorak is Mythic. Around level 250 things started to get sketchy and have since switched to using
[6021,6787,1201,6409,3021,1,3,2,1,2,3,2,14017]
Taking advantage of Thief’s Stealthy and summons, allowing time to pick off all the threats.