Also, I did the Cursed Thrall one with Sunsinger's Flame Shield. It was a bit slow waiting for the recharge as I don't have augments to speed it up (I tend to prefer restoring grenade energy on melee) but I took them one by one in The Wakening and got it fine. There's a staircase leading down into the first room where they all spawn in a big group, you can stand there and they won't follow you. Good place to recharge and soften em up a bit if you want to be sure of a one hit kill.