I took a look at what spells you were casting in your second wipe versus one of my earlier kills of similar length to see what you are casting. A quick look is showing me that you only cast Wake of Ashes 6 times and the number of times you used Divine Storm is low as well considering there are a lot of eyes that pop up and sometimes in locations that take too long to get to (right behind Guldan for example). Wake will definitely help boost you up a little bit as well as using Divine Storm since you have two relics that boost that. The last thing I saw was that you wasted a fair bit of Holy Power, it is going to be unavoidable from the tier set but the wasted portion from Wake of Ashes should be a bit lower.