Ursula maybe?
As long as she has low accuracy, she should be fine. Try if using her speed aura can help speed up a bit but I worried if Doompriest can still work as effective with her current speed right now. I wanted her to be slower than the boss so she can cleanse after the boss places hp burn. Though I am not sure if being faster than the boss is much better.
I also tried 250+ speed Doompriest but my runs always fail. Not sure if her speed being faster than the boss is the problem since I also tweaked the gears of my other champs when it worked.